SECTION 5-2
                          Medians and Altitudes of Triangles




Thursday, March 1, 2012
ESSENTIAL QUESTIONS


                      How do you identify and use medians in triangles?


                      How do you identify and use altitudes in triangles?




Thursday, March 1, 2012
VOCABULARY
         1. Median:


         2. Centroid:


         3. Altitude:



         4. Orthocenter:


Thursday, March 1, 2012
VOCABULARY
         1. Median: A segment in a triangle that connects a vertex to
            the midpoint of the opposite side

         2. Centroid:


         3. Altitude:



         4. Orthocenter:


Thursday, March 1, 2012
VOCABULARY
         1. Median: A segment in a triangle that connects a vertex to
            the midpoint of the opposite side

         2. Centroid: The point of concurrency where the medians
            intersect in a triangle (always inside)

         3. Altitude:



         4. Orthocenter:


Thursday, March 1, 2012
VOCABULARY
         1. Median: A segment in a triangle that connects a vertex to
            the midpoint of the opposite side

         2. Centroid: The point of concurrency where the medians
            intersect in a triangle (always inside)

         3. Altitude: A segment in a triangle that connects a vertex to
            the opposite side so that the side and altitude are
            perpendicular

         4. Orthocenter:


Thursday, March 1, 2012
VOCABULARY
         1. Median: A segment in a triangle that connects a vertex to
            the midpoint of the opposite side

         2. Centroid: The point of concurrency where the medians
            intersect in a triangle (always inside)

         3. Altitude: A segment in a triangle that connects a vertex to
            the opposite side so that the side and altitude are
            perpendicular

         4. Orthocenter: The point of concurrency where the altitudes
            of a triangle intersect

Thursday, March 1, 2012
5.7 - CENTROID THEOREM

               The centroid of a triangle is two-thirds the distance from each vertex
                               to the midpoint of the opposite side




Thursday, March 1, 2012
5.7 - CENTROID THEOREM

               The centroid of a triangle is two-thirds the distance from each vertex
                               to the midpoint of the opposite side


                                          If G is the centroid of ∆ABC, then
                                             2         2            2
                                         AG = AF , BG = BD, and CG = CE
                                             3         3            3




Thursday, March 1, 2012
Special Segments and Points in Triangles
                                           Point of        Special
                 Name         Example                                        Example
                                         Concurrency      Property


        Perpendicular                                   Circumcenter is
                                        Circumcenter    equidistant from
           Bisector                                       each vertex




                Angle                                     In center is
                                          Incenter      equidistant from
               Bisector                                    each side



                                                         Centroid is two-
                                                       thirds the distance
               Median                     Centroid        from vertex to
                                                       opposite midpoint



                                                         Altitudes are
               Altitude                 Orthocenter      concurrent at
                                                          orthocenter




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV
                                           3




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV
                                           3
                                           2
                                       YP = (12)
                                           3




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV
                                           3
                                           2
                                       YP = (12)
                                           3
                                         YP = 8




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV          PV = YV − YP
                                           3
                                           2
                                       YP = (12)
                                           3
                                         YP = 8




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV          PV = YV − YP
                                           3
                                           2
                                       YP = (12)         PV = 12 − 8
                                           3
                                         YP = 8




Thursday, March 1, 2012
EXAMPLE 1
               In ∆XYZ, P is the centroid and YV = 12. Find YP and PV.


                                           2
                                       YP = YV          PV = YV − YP
                                           3
                                           2
                                       YP = (12)         PV = 12 − 8
                                           3
                                         YP = 8            PV = 4




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE
                                       3




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE
                                       3

                                       2
                                    4 = CE
                                       3




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE
                                       3

                                       2
                                    4 = CE
                                       3
                                     CE = 6




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE            GE = CE − CG
                                       3

                                       2
                                    4 = CE
                                       3
                                     CE = 6




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE            GE = CE − CG
                                       3

                                       2
                                    4 = CE             GE = 6 − 4
                                       3
                                     CE = 6




Thursday, March 1, 2012
EXAMPLE 2
                          In ∆ABC, CG = 4. Find GE.


                                       2
                                   CG = CE            GE = CE − CG
                                       3

                                       2
                                    4 = CE             GE = 6 − 4
                                       3
                                     CE = 6              GE = 2




Thursday, March 1, 2012
EXAMPLE 3

             An artist is designing a sculpture that balances a triangle on
             tip of a pole. In the artistʼs design on the coordinate plane,
             the vertices are located at (1, 4), (3, 0), and (3, 8). What are
              the coordinates of the point where the artist should place
                  the pole under the triangle so that is will balance?




Thursday, March 1, 2012
EXAMPLE 3
                                (1, 4), (3, 0), (3, 8)




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     (1, 4), (3, 0), (3, 8)




                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     (1, 4), (3, 0), (3, 8)




                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     (1, 4), (3, 0), (3, 8)




                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x
                                          ⎛ 3 + 3 0 + 8⎞
                                       M =⎜      ,     ⎟
                                          ⎝ 2       2 ⎠




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x
                                          ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞
                                       M =⎜      ,     ⎟ = ⎜ 2 , 2⎟
                                          ⎝ 2       2 ⎠ ⎝         ⎠




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x
                                          ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞
                                       M =⎜      ,     ⎟ = ⎜ 2 , 2⎟
                                          ⎝ 2       2 ⎠ ⎝         ⎠
                                            ( )
                                          = 3,4



Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x
                                          ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞
                                       M =⎜      ,     ⎟ = ⎜ 2 , 2⎟
                                          ⎝ 2       2 ⎠ ⎝         ⎠
                                            ( )
                                          = 3,4



Thursday, March 1, 2012
EXAMPLE 3
                          y
                                            (1, 4), (3, 0), (3, 8)

                                     We need to find the centroid, so
                                     we start by finding the midpoint
                                           of our vertical side.
                                 x
                                          ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞
                                       M =⎜      ,     ⎟ = ⎜ 2 , 2⎟
                                          ⎝ 2       2 ⎠ ⎝         ⎠
                                            ( )
                                          = 3,4



Thursday, March 1, 2012
EXAMPLE 3
                          y




                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     Next, we need the distance from
                                       the opposite vertex to this
                                               midpoint.

                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     Next, we need the distance from
                                       the opposite vertex to this
                                               midpoint.
                                          d = (1 − 3)2 + (4 − 4)2
                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     Next, we need the distance from
                                       the opposite vertex to this
                                               midpoint.
                                          d = (1 − 3)2 + (4 − 4)2
                                 x
                                             = (−2) + 0
                                                     2    2




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     Next, we need the distance from
                                       the opposite vertex to this
                                               midpoint.
                                          d = (1 − 3)2 + (4 − 4)2
                                 x
                                             = (−2) + 0
                                                     2    2



                                               = 4




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     Next, we need the distance from
                                       the opposite vertex to this
                                               midpoint.
                                          d = (1 − 3)2 + (4 − 4)2
                                 x
                                             = (−2) + 0
                                                     2    2



                                               = 4 =2




Thursday, March 1, 2012
EXAMPLE 3
                          y




                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     The centroid P is 2/3 of this
                                      distance from the vertex.



                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     The centroid P is 2/3 of this
                                      distance from the vertex.
                                               ⎛ 2        ⎞
                                           P = ⎜1 + (2),4 ⎟
                                               ⎝ 3        ⎠
                                 x




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     The centroid P is 2/3 of this
                                      distance from the vertex.
                                               ⎛ 2        ⎞
                                           P = ⎜1 + (2),4 ⎟
                                               ⎝ 3        ⎠
                                 x               ⎛ 4 ⎞
                                             P = ⎜1 + ,4 ⎟
                                                 ⎝ 3 ⎠




Thursday, March 1, 2012
EXAMPLE 3
                          y
                                     The centroid P is 2/3 of this
                                      distance from the vertex.
                                               ⎛ 2        ⎞
                                           P = ⎜1 + (2),4 ⎟
                                               ⎝ 3        ⎠
                                 x               ⎛ 4 ⎞
                                             P = ⎜1 + ,4 ⎟
                                                 ⎝ 3 ⎠

                                                  ⎛7 ⎞
                                              P = ⎜ ,4 ⎟
                                                  ⎝3 ⎠


Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y




                                           x




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y


                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y


                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y


                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                   −5 + 3




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                           4
                                                   −5 + 3 −2




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                           4
                                                   −5 + 3 −2
                                                             = −2




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                           4
                                                   −5 + 3 −2
                                                             = −2 ⊥ m =
                                                                        1
                                                                        2




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                           4
                                                   −5 + 3 −2
                                                             = −2 ⊥ m =
                                                                        1
                                                                        2

                                                ( )
                                             m HJ =
                                                    2 −1
                                                    1+ 5

Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                   −5 + 3 −2
                                                            4
                                                              = −2 ⊥ m =
                                                                         1
                                                                         2

                                                ( )
                                             m HJ =
                                                    2 −1 1
                                                    1+ 5 6
                                                          =


Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                            To find the orthocenter, find the
                                             intersection of two altitudes.
                                  H
                          J                    Let’s find the equations for the
                                               altitudes coming from I and H.
                                           x
                              I                ( )
                                            m JI =
                                                   1+ 3
                                                         =
                                                   −5 + 3 −2
                                                            4
                                                              = −2 ⊥ m =
                                                                          1
                                                                          2

                                                ( )
                                             m HJ =
                                                    2 −1 1
                                                    1+ 5 6
                                                          =      ⊥ m = −6


Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                    Altitude through H

                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                    Altitude through H
                                                           1
                                                      ⊥ m = , (1,2)
                                  H                        2
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                    Altitude through H
                                                             1
                                                      ⊥ m = , (1,2)
                                  H                          2
                          J                                  1
                                                      y − 2 = (x −1)
                                                             2
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                    Altitude through H
                                                             1
                                                      ⊥ m = , (1,2)
                                  H                          2
                          J                                  1
                                                      y − 2 = (x −1)
                                                             2
                                           x                  1   1
                              I                       y−2= x −
                                                              2   2




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                    Altitude through H
                                                             1
                                                      ⊥ m = , (1,2)
                                  H                          2
                          J                                   1
                                                      y − 2 = (x −1)
                                                              2
                                           x                  1    1
                              I                       y−2= x −
                                                              2    2
                                                            1    3
                                                        y= x+
                                                            2    2

Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                     Altitude through I

                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                     Altitude through I
                                                    ⊥ m = −6, (−3,−3)
                                  H
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                     Altitude through I
                                                    ⊥ m = −6, (−3,−3)
                                  H                   y + 3 = −6(x + 3)
                          J
                                           x
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                     Altitude through I
                                                    ⊥ m = −6, (−3,−3)
                                  H                   y + 3 = −6(x + 3)
                          J
                                           x          y + 3 = −6x −18
                              I




Thursday, March 1, 2012
EXAMPLE 4
                 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1).
                   Find the coordinates of the orthocenter of ∆HIJ.
                            y
                                                     Altitude through I
                                                    ⊥ m = −6, (−3,−3)
                                  H                   y + 3 = −6(x + 3)
                          J
                                           x          y + 3 = −6x −18
                              I                        y = −6x − 21




Thursday, March 1, 2012
EXAMPLE 4




Thursday, March 1, 2012
EXAMPLE 4
                        1    3
              −6x − 21 = x +
                        2    2




Thursday, March 1, 2012
EXAMPLE 4
                         1   3
              −6x − 21 = x +
                         2   2
              +6x       +6x




Thursday, March 1, 2012
EXAMPLE 4
                         1   3
              −6x − 21 = x +
                         2   2
              +6x       +6x
                          13   3
                     −21 = x +
                           2   2




Thursday, March 1, 2012
EXAMPLE 4
                         1   3
              −6x − 21 = x +
                         2   2
              +6x       +6x
                          13   3
                     −21 = x +
                           2   2
                       3       3
                     −       −
                       2       2




Thursday, March 1, 2012
EXAMPLE 4
                         1   3
              −6x − 21 = x +
                         2   2
              +6x       +6x
                          13   3
                     −21 = x +
                           2   2
                       3       3
                     −       −
                       2       2
                           45 13
                          − = x
                           2   2



Thursday, March 1, 2012
EXAMPLE 4
                         1   3        2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2
              −6x − 21 = x +            ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13
                         2   2       13 ⎝     ⎠ ⎝       ⎠
              +6x       +6x
                          13   3
                     −21 = x +
                           2   2
                       3       3
                     −       −
                       2       2
                           45 13
                          − = x
                           2   2



Thursday, March 1, 2012
EXAMPLE 4
                         1   3        2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2
              −6x − 21 = x +            ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13
                         2   2       13 ⎝     ⎠ ⎝       ⎠
              +6x       +6x
                                                45
                          13   3            x=−
                     −21 = x +                  13
                           2   2
                       3       3
                     −       −
                       2       2
                           45 13
                          − = x
                           2   2



Thursday, March 1, 2012
EXAMPLE 4
                         1   3          2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2
              −6x − 21 = x +              ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13
                         2   2         13 ⎝     ⎠ ⎝       ⎠
              +6x       +6x
                                                  45
                          13   3              x=−
                     −21 = x +                    13
                           2   2
                                       ⎛ 45 ⎞      1 ⎛ 45 ⎞ 3
                       3       3    −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ +
                     −       −         ⎝ 13 ⎠      2 ⎝ 13 ⎠ 2
                       2       2
                           45 13
                          − = x
                           2   2



Thursday, March 1, 2012
EXAMPLE 4
                         1   3          2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2
              −6x − 21 = x +              ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13
                         2   2         13 ⎝     ⎠ ⎝       ⎠
              +6x       +6x
                                                  45
                          13   3              x=−
                     −21 = x +                    13
                           2   2
                                       ⎛ 45 ⎞      1 ⎛ 45 ⎞ 3
                       3       3    −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ +
                     −       −         ⎝ 13 ⎠      2 ⎝ 13 ⎠ 2
                       2       2
                           45 13              3   3
                          − = x             − =−
                           2   2             13  13



Thursday, March 1, 2012
EXAMPLE 4
                         1   3          2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2
              −6x − 21 = x +              ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13
                         2   2         13 ⎝     ⎠ ⎝       ⎠
              +6x       +6x
                                                  45
                          13   3              x=−
                     −21 = x +                    13
                           2   2
                                       ⎛ 45 ⎞      1 ⎛ 45 ⎞ 3
                       3       3    −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ +
                     −       −         ⎝ 13 ⎠      2 ⎝ 13 ⎠ 2
                       2       2
                           45 13              3   3
                          − = x             − =−
                           2   2             13  13              ⎛ 45 3 ⎞
                                                                 ⎜ − 13 ,− 13 ⎟
                                                                 ⎝            ⎠


Thursday, March 1, 2012
CHECK YOUR
                          UNDERSTANDING



                              p. 337 #1-4




Thursday, March 1, 2012
PROBLEM SET




Thursday, March 1, 2012
PROBLEM SET


                                    p. 338 #5-31 odd, 49, 53




                    "Education's purpose is to replace an empty mind with an open
                                      one." – Malcolm Forbes

Thursday, March 1, 2012

Geometry Section 5-2 1112

  • 1.
    SECTION 5-2 Medians and Altitudes of Triangles Thursday, March 1, 2012
  • 2.
    ESSENTIAL QUESTIONS How do you identify and use medians in triangles? How do you identify and use altitudes in triangles? Thursday, March 1, 2012
  • 3.
    VOCABULARY 1. Median: 2. Centroid: 3. Altitude: 4. Orthocenter: Thursday, March 1, 2012
  • 4.
    VOCABULARY 1. Median: A segment in a triangle that connects a vertex to the midpoint of the opposite side 2. Centroid: 3. Altitude: 4. Orthocenter: Thursday, March 1, 2012
  • 5.
    VOCABULARY 1. Median: A segment in a triangle that connects a vertex to the midpoint of the opposite side 2. Centroid: The point of concurrency where the medians intersect in a triangle (always inside) 3. Altitude: 4. Orthocenter: Thursday, March 1, 2012
  • 6.
    VOCABULARY 1. Median: A segment in a triangle that connects a vertex to the midpoint of the opposite side 2. Centroid: The point of concurrency where the medians intersect in a triangle (always inside) 3. Altitude: A segment in a triangle that connects a vertex to the opposite side so that the side and altitude are perpendicular 4. Orthocenter: Thursday, March 1, 2012
  • 7.
    VOCABULARY 1. Median: A segment in a triangle that connects a vertex to the midpoint of the opposite side 2. Centroid: The point of concurrency where the medians intersect in a triangle (always inside) 3. Altitude: A segment in a triangle that connects a vertex to the opposite side so that the side and altitude are perpendicular 4. Orthocenter: The point of concurrency where the altitudes of a triangle intersect Thursday, March 1, 2012
  • 8.
    5.7 - CENTROIDTHEOREM The centroid of a triangle is two-thirds the distance from each vertex to the midpoint of the opposite side Thursday, March 1, 2012
  • 9.
    5.7 - CENTROIDTHEOREM The centroid of a triangle is two-thirds the distance from each vertex to the midpoint of the opposite side If G is the centroid of ∆ABC, then 2 2 2 AG = AF , BG = BD, and CG = CE 3 3 3 Thursday, March 1, 2012
  • 10.
    Special Segments andPoints in Triangles Point of Special Name Example Example Concurrency Property Perpendicular Circumcenter is Circumcenter equidistant from Bisector each vertex Angle In center is Incenter equidistant from Bisector each side Centroid is two- thirds the distance Median Centroid from vertex to opposite midpoint Altitudes are Altitude Orthocenter concurrent at orthocenter Thursday, March 1, 2012
  • 11.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. Thursday, March 1, 2012
  • 12.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV 3 Thursday, March 1, 2012
  • 13.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV 3 2 YP = (12) 3 Thursday, March 1, 2012
  • 14.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV 3 2 YP = (12) 3 YP = 8 Thursday, March 1, 2012
  • 15.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV PV = YV − YP 3 2 YP = (12) 3 YP = 8 Thursday, March 1, 2012
  • 16.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV PV = YV − YP 3 2 YP = (12) PV = 12 − 8 3 YP = 8 Thursday, March 1, 2012
  • 17.
    EXAMPLE 1 In ∆XYZ, P is the centroid and YV = 12. Find YP and PV. 2 YP = YV PV = YV − YP 3 2 YP = (12) PV = 12 − 8 3 YP = 8 PV = 4 Thursday, March 1, 2012
  • 18.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. Thursday, March 1, 2012
  • 19.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE 3 Thursday, March 1, 2012
  • 20.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE 3 2 4 = CE 3 Thursday, March 1, 2012
  • 21.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE 3 2 4 = CE 3 CE = 6 Thursday, March 1, 2012
  • 22.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE GE = CE − CG 3 2 4 = CE 3 CE = 6 Thursday, March 1, 2012
  • 23.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE GE = CE − CG 3 2 4 = CE GE = 6 − 4 3 CE = 6 Thursday, March 1, 2012
  • 24.
    EXAMPLE 2 In ∆ABC, CG = 4. Find GE. 2 CG = CE GE = CE − CG 3 2 4 = CE GE = 6 − 4 3 CE = 6 GE = 2 Thursday, March 1, 2012
  • 25.
    EXAMPLE 3 An artist is designing a sculpture that balances a triangle on tip of a pole. In the artistʼs design on the coordinate plane, the vertices are located at (1, 4), (3, 0), and (3, 8). What are the coordinates of the point where the artist should place the pole under the triangle so that is will balance? Thursday, March 1, 2012
  • 26.
    EXAMPLE 3 (1, 4), (3, 0), (3, 8) Thursday, March 1, 2012
  • 27.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) x Thursday, March 1, 2012
  • 28.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) x Thursday, March 1, 2012
  • 29.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) x Thursday, March 1, 2012
  • 30.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x Thursday, March 1, 2012
  • 31.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x ⎛ 3 + 3 0 + 8⎞ M =⎜ , ⎟ ⎝ 2 2 ⎠ Thursday, March 1, 2012
  • 32.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞ M =⎜ , ⎟ = ⎜ 2 , 2⎟ ⎝ 2 2 ⎠ ⎝ ⎠ Thursday, March 1, 2012
  • 33.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞ M =⎜ , ⎟ = ⎜ 2 , 2⎟ ⎝ 2 2 ⎠ ⎝ ⎠ ( ) = 3,4 Thursday, March 1, 2012
  • 34.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞ M =⎜ , ⎟ = ⎜ 2 , 2⎟ ⎝ 2 2 ⎠ ⎝ ⎠ ( ) = 3,4 Thursday, March 1, 2012
  • 35.
    EXAMPLE 3 y (1, 4), (3, 0), (3, 8) We need to find the centroid, so we start by finding the midpoint of our vertical side. x ⎛ 3 + 3 0 + 8⎞ ⎛ 6 8⎞ M =⎜ , ⎟ = ⎜ 2 , 2⎟ ⎝ 2 2 ⎠ ⎝ ⎠ ( ) = 3,4 Thursday, March 1, 2012
  • 36.
    EXAMPLE 3 y x Thursday, March 1, 2012
  • 37.
    EXAMPLE 3 y Next, we need the distance from the opposite vertex to this midpoint. x Thursday, March 1, 2012
  • 38.
    EXAMPLE 3 y Next, we need the distance from the opposite vertex to this midpoint. d = (1 − 3)2 + (4 − 4)2 x Thursday, March 1, 2012
  • 39.
    EXAMPLE 3 y Next, we need the distance from the opposite vertex to this midpoint. d = (1 − 3)2 + (4 − 4)2 x = (−2) + 0 2 2 Thursday, March 1, 2012
  • 40.
    EXAMPLE 3 y Next, we need the distance from the opposite vertex to this midpoint. d = (1 − 3)2 + (4 − 4)2 x = (−2) + 0 2 2 = 4 Thursday, March 1, 2012
  • 41.
    EXAMPLE 3 y Next, we need the distance from the opposite vertex to this midpoint. d = (1 − 3)2 + (4 − 4)2 x = (−2) + 0 2 2 = 4 =2 Thursday, March 1, 2012
  • 42.
    EXAMPLE 3 y x Thursday, March 1, 2012
  • 43.
    EXAMPLE 3 y The centroid P is 2/3 of this distance from the vertex. x Thursday, March 1, 2012
  • 44.
    EXAMPLE 3 y The centroid P is 2/3 of this distance from the vertex. ⎛ 2 ⎞ P = ⎜1 + (2),4 ⎟ ⎝ 3 ⎠ x Thursday, March 1, 2012
  • 45.
    EXAMPLE 3 y The centroid P is 2/3 of this distance from the vertex. ⎛ 2 ⎞ P = ⎜1 + (2),4 ⎟ ⎝ 3 ⎠ x ⎛ 4 ⎞ P = ⎜1 + ,4 ⎟ ⎝ 3 ⎠ Thursday, March 1, 2012
  • 46.
    EXAMPLE 3 y The centroid P is 2/3 of this distance from the vertex. ⎛ 2 ⎞ P = ⎜1 + (2),4 ⎟ ⎝ 3 ⎠ x ⎛ 4 ⎞ P = ⎜1 + ,4 ⎟ ⎝ 3 ⎠ ⎛7 ⎞ P = ⎜ ,4 ⎟ ⎝3 ⎠ Thursday, March 1, 2012
  • 47.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. Thursday, March 1, 2012
  • 48.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y x Thursday, March 1, 2012
  • 49.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y H J x I Thursday, March 1, 2012
  • 50.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y H J x I Thursday, March 1, 2012
  • 51.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y H J x I Thursday, March 1, 2012
  • 52.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J x I Thursday, March 1, 2012
  • 53.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I Thursday, March 1, 2012
  • 54.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 −5 + 3 Thursday, March 1, 2012
  • 55.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = 4 −5 + 3 −2 Thursday, March 1, 2012
  • 56.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = 4 −5 + 3 −2 = −2 Thursday, March 1, 2012
  • 57.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = 4 −5 + 3 −2 = −2 ⊥ m = 1 2 Thursday, March 1, 2012
  • 58.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = 4 −5 + 3 −2 = −2 ⊥ m = 1 2 ( ) m HJ = 2 −1 1+ 5 Thursday, March 1, 2012
  • 59.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = −5 + 3 −2 4 = −2 ⊥ m = 1 2 ( ) m HJ = 2 −1 1 1+ 5 6 = Thursday, March 1, 2012
  • 60.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y To find the orthocenter, find the intersection of two altitudes. H J Let’s find the equations for the altitudes coming from I and H. x I ( ) m JI = 1+ 3 = −5 + 3 −2 4 = −2 ⊥ m = 1 2 ( ) m HJ = 2 −1 1 1+ 5 6 = ⊥ m = −6 Thursday, March 1, 2012
  • 61.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through H H J x I Thursday, March 1, 2012
  • 62.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through H 1 ⊥ m = , (1,2) H 2 J x I Thursday, March 1, 2012
  • 63.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through H 1 ⊥ m = , (1,2) H 2 J 1 y − 2 = (x −1) 2 x I Thursday, March 1, 2012
  • 64.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through H 1 ⊥ m = , (1,2) H 2 J 1 y − 2 = (x −1) 2 x 1 1 I y−2= x − 2 2 Thursday, March 1, 2012
  • 65.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through H 1 ⊥ m = , (1,2) H 2 J 1 y − 2 = (x −1) 2 x 1 1 I y−2= x − 2 2 1 3 y= x+ 2 2 Thursday, March 1, 2012
  • 66.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through I H J x I Thursday, March 1, 2012
  • 67.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through I ⊥ m = −6, (−3,−3) H J x I Thursday, March 1, 2012
  • 68.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through I ⊥ m = −6, (−3,−3) H y + 3 = −6(x + 3) J x I Thursday, March 1, 2012
  • 69.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through I ⊥ m = −6, (−3,−3) H y + 3 = −6(x + 3) J x y + 3 = −6x −18 I Thursday, March 1, 2012
  • 70.
    EXAMPLE 4 The vertices of ∆HIJ are H(1, 2), I(−3, −3), and J(−5, 1). Find the coordinates of the orthocenter of ∆HIJ. y Altitude through I ⊥ m = −6, (−3,−3) H y + 3 = −6(x + 3) J x y + 3 = −6x −18 I y = −6x − 21 Thursday, March 1, 2012
  • 71.
  • 72.
    EXAMPLE 4 1 3 −6x − 21 = x + 2 2 Thursday, March 1, 2012
  • 73.
    EXAMPLE 4 1 3 −6x − 21 = x + 2 2 +6x +6x Thursday, March 1, 2012
  • 74.
    EXAMPLE 4 1 3 −6x − 21 = x + 2 2 +6x +6x 13 3 −21 = x + 2 2 Thursday, March 1, 2012
  • 75.
    EXAMPLE 4 1 3 −6x − 21 = x + 2 2 +6x +6x 13 3 −21 = x + 2 2 3 3 − − 2 2 Thursday, March 1, 2012
  • 76.
    EXAMPLE 4 1 3 −6x − 21 = x + 2 2 +6x +6x 13 3 −21 = x + 2 2 3 3 − − 2 2 45 13 − = x 2 2 Thursday, March 1, 2012
  • 77.
    EXAMPLE 4 1 3 2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2 −6x − 21 = x + ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13 2 2 13 ⎝ ⎠ ⎝ ⎠ +6x +6x 13 3 −21 = x + 2 2 3 3 − − 2 2 45 13 − = x 2 2 Thursday, March 1, 2012
  • 78.
    EXAMPLE 4 1 3 2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2 −6x − 21 = x + ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13 2 2 13 ⎝ ⎠ ⎝ ⎠ +6x +6x 45 13 3 x=− −21 = x + 13 2 2 3 3 − − 2 2 45 13 − = x 2 2 Thursday, March 1, 2012
  • 79.
    EXAMPLE 4 1 3 2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2 −6x − 21 = x + ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13 2 2 13 ⎝ ⎠ ⎝ ⎠ +6x +6x 45 13 3 x=− −21 = x + 13 2 2 ⎛ 45 ⎞ 1 ⎛ 45 ⎞ 3 3 3 −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ + − − ⎝ 13 ⎠ 2 ⎝ 13 ⎠ 2 2 2 45 13 − = x 2 2 Thursday, March 1, 2012
  • 80.
    EXAMPLE 4 1 3 2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2 −6x − 21 = x + ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13 2 2 13 ⎝ ⎠ ⎝ ⎠ +6x +6x 45 13 3 x=− −21 = x + 13 2 2 ⎛ 45 ⎞ 1 ⎛ 45 ⎞ 3 3 3 −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ + − − ⎝ 13 ⎠ 2 ⎝ 13 ⎠ 2 2 2 45 13 3 3 − = x − =− 2 2 13 13 Thursday, March 1, 2012
  • 81.
    EXAMPLE 4 1 3 2 ⎛ 45 ⎞ ⎛ 13 ⎞ 2 −6x − 21 = x + ⎜ − 2 ⎟ = ⎜ 2 x ⎟ 13 2 2 13 ⎝ ⎠ ⎝ ⎠ +6x +6x 45 13 3 x=− −21 = x + 13 2 2 ⎛ 45 ⎞ 1 ⎛ 45 ⎞ 3 3 3 −6 ⎜ − ⎟ − 21 = ⎜ − ⎟ + − − ⎝ 13 ⎠ 2 ⎝ 13 ⎠ 2 2 2 45 13 3 3 − = x − =− 2 2 13 13 ⎛ 45 3 ⎞ ⎜ − 13 ,− 13 ⎟ ⎝ ⎠ Thursday, March 1, 2012
  • 82.
    CHECK YOUR UNDERSTANDING p. 337 #1-4 Thursday, March 1, 2012
  • 83.
  • 84.
    PROBLEM SET p. 338 #5-31 odd, 49, 53 "Education's purpose is to replace an empty mind with an open one." – Malcolm Forbes Thursday, March 1, 2012