The document discusses congruence and triangles. It defines congruent figures as those where all corresponding parts are equal in measure. It presents the Third Angle Theorem, which states that if two angles in one triangle are equal to two angles in another triangle, then the third angles are also equal. It also outlines three properties of congruent triangles: reflexive, symmetric, and transitive properties. The homework assigned is problems #3-15 odd, 19-21, and 26 on page 228.

1. 4.2 Congruence & Triangles October 11, 2012
4.2 Congruence & Triangles
Congruent Figures: all of the parts in 1 figure are ≅ to the
corresponding parts of the other.
Oct 15­2:30 PM
HW pg. 228 #3­15 odd, 19­21, 26 1

2. 4.2 Congruence & Triangles October 11, 2012
Oct 15­2:34 PM
HW pg. 228 #3­15 odd, 19­21, 26 2

3. 4.2 Congruence & Triangles October 11, 2012
Third Angle Theorem
If 2 angles in one ∆ are = in measure to 2 angles of another ∆,
then the 3 rd angle in each triangle are ≅ .
B E
<A ≅ <D & <B ≅ <E;
therefore <C ≅ <F
C F
A D
Oct 15­2:28 PM
HW pg. 228 #3­15 odd, 19­21, 26 3

4. 4.2 Congruence & Triangles October 11, 2012
Oct 15­2:41 PM
HW pg. 228 #3­15 odd, 19­21, 26 4

5. 4.2 Congruence & Triangles October 11, 2012
Theorem 4.4 Properties of Congruent Triangles
Reflexive: ABC ≅ ABC
Symmetric: If ABC ≅ DEF, then DEF ≅ ABC
Transitive: If ABC ≅ DEF & DEF ≅ JKL,
then ABC ≅ JKL
Oct 15­2:39 PM
HW pg. 228 #3­15 odd, 19­21, 26 5

6. 4.2 Congruence & Triangles October 11, 2012
HW pg. 228 #3-15 odd, 19-21 & 26
Oct 15­2:49 PM
HW pg. 228 #3­15 odd, 19­21, 26 6