The Cavite Mutiny of 1872 was an uprising of military personnel of Fort San Felipe, the Spanish arsenal in Cavite, Philippines on January 20, 1872, about 200 Filipino military personnel of Fort San Felipe Arsenal in Cavite, Philippines, staged a mutiny which in a way led to the Philippine Revolution in 1896. The 1872 Cavite Mutiny was precipitated by the removal of long-standing personal benefits to the workers such as tax (tribute) and forced labor exemptions on order from the Governor General Rafael de Izquierdo. Many scholars believe that the Cavite Mutiny of 1872 was the beginning of Filipino nationalism that would eventually lead to the Philippine Revolution of 1896.
2. 2
Module 5: Functions and Relations
Definition of Terms
Domain and Range
Graphical Representation of Functions
Operations on Functions
Graphs and Equations
3. 3
Theorem 5.56. In a right triangle, if π and π are the lengths of the perpendicular
sides and π is the length of the hypotenuse, then π2
= π2
+ π2
.
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
π¦
π
π
π
4. 4
Theorem 5.57. The distance between two points π1(π₯1, π¦1) and π2(π₯2, π¦2) is given
by π1π2 = π₯2 β π₯1
2 + π¦2 β π¦1
2.
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
π¦
π2(π₯2,π¦2)
π1(π₯1, π¦1)
π¦2 β π¦1
π₯2 β π₯1
Illustration.
The distance between the two points
π1(β2, 1) and π2(4, 7) is
π1π2 = 4 β (β2) 2 + 7 β 1 2
= 62 + 62
= 6 2 units.
5. 5
The distance between two points π1(π₯1, π¦1) and π2(π₯2, π¦2) in a horizontal segment
is given by π1π2 = π₯2 β π₯1
2 + π¦1 β π¦1
2 = π₯2 β π₯1
2 = π₯2 β π₯1 .
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
π¦
π2(π₯2, π¦1)
π1(π₯1, π¦1)
π1π2
Illustration.
The distance between the two points
π1(β7, 7) and π2(5, 7) is
π1π2 = 5 β (β7)
= 12 units.
6. 6
The distance between two points π1(π₯1, π¦1) and π2(π₯1, π¦2) in a vertical segment is
given by π1π2 = π₯1 β π₯1
2 + π¦1 β π¦1
2 = π¦2 β π¦1
2 = π¦2 β π¦1 .
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
π¦
π2(π₯1, π¦2)
π1(π₯1, π¦1)
π1π2
Illustration.
The distance between the two points
π1(7, 5) and π2(7, β7) is
π1π2 = β7 β 5
= 12 units.
7. 7
Theorem 5.58. If π, π and π are the lengths of the sides of a triangle and π2 =
π2 + π2, then the triangle is a right triangle, and π is the length of the hypotenuse
side.
-12 -10 -8 -6 -4 -2 2 4 6 8 10 12
-12
-8
-4
4
8
12
π₯
π¦
Example 5.59. Show that the points π(1, 2), π(4, 7), and π (β9, 8) are vertices of
a right triangle.
π(1, 2)
π(4, 7)
π (β9, 8)
Solution: Applying Theorem 5.58, we have ππ =
4 β 1 2 + 7 β 2 2 = 34,
ππ = β9 β 1 2 + 8 β 2 2 = 136, and
ππ = β9 β 4 2 + 8 β 7 2 = 170. Observe
that
ππ
2
+ ππ
2
= 34
2
+ 136
2
= 170
= ππ
2
.
Thus the given 3 points are vertices of a right triangle.
8. 8
Definition 5.60 (Midpoint). If π(π₯, π¦) is the midpoint of the line segment from
π1(π₯1, π¦1) and π2(π₯2, π¦2), then π₯ =
π₯1+π₯2
2
and π¦ =
π¦1+π¦2
2
.
Definition 5.60 (Median). A median of a triangle is a line segment from a vertex
to the midpoint of the opposite side.
Example 5.61. Find the length of the medians of the triangle having vertices
π΄(2, 3), π΅(3, β3) and πΆ(β1, β1).
Solution.
-12 -10 -8 -6 -4 -2 2 4 6 8 10 12
-12
-8
-4
4
8
12
π₯
π΄(2, 3)
π΅(3, β3)
πΆ(β1,β1)
Let the midpoint of π΄π΅, π΄πΆ and π΅πΆ be respectively, π,
π and π. Then
π π₯, π¦ = π
2+3
2
,
3+(β3)
2
= π
5
2
, 0 ,
π π₯, π¦ = π
2+(β1)
2
,
3+(β1)
2
= π
1
2
, 1 ,
π
5
2
, 0
π
1
2
, 1
π(1,β2)
9. 9
and π π₯, π¦ = π
3+(β1)
2
,
β3+(β1)
2
= π(1, β2).
Thus the lengths of the median are
π΄π = 1 β 2 2 + β2 β 3 2 = 26 units,
π΅π =
1
2
β 3
2
+ 1 β (β3) 2 =
89
4
=
1
2
89 units, and
πΆπ =
5
2
β (β1)
2
+ 0 β (β1) 2 =
53
4
=
1
2
53 units.
Definition 5.62 (Slope). If π1(π₯1, π¦1) and π2(π₯2, π¦2) are any two distinct points on
line π, which is not parallel to the π¦ axis, then the slope of π, denoted by π, is given
by
π =
π¦2βπ¦1
π₯2βπ₯1
.
10. 10
Note:
1. From Definition 5.62 we see that if π(π₯, π¦) and π1(π₯1, π¦1) are any points on a
line then the point-slope form of an equation of the line is
π¦ β π¦1 = π π₯ β π₯1 .
2. If in the point-slope form we choose the particular point (0, π), that is, the point
where the line intersects the π¦ axis, for the point π₯1, π¦1 , we have
π¦ β π = π π₯ β 0 βΊ π¦ = ππ₯ + π
and this is called the slope-intercept form of an equation of the line.
Theorem 5.63.
(i) An equation of the vertical line having π₯ intercept π is π₯ = π.
(ii) An equation of the horizontal line having π¦ intercept π is π¦ = π.
11. 11
Theorem 5.63.
(i) An equation of the vertical line having π₯ intercept π is π₯ = π.
(ii) An equation of the horizontal line having π¦ intercept π is π¦ = π.
Theorem 5.64. The graph of the equation π΄π₯ + π΅π¦ + πΆ = 0 where π΄, π΅, and πΆ are
constants and where not both π΄ and π΅ are zero is line.
Theorem 5.65. If π1 and π2 are two distinct nonvertical lines having slopes π1 and
π2, respectively, then π1 and π2 are parallel if and only if π1 = π2.
Theorem 5.66. Two nonvertical lines π1 and π2, having slopes π1 and π2,
respectively, are perpendicular if and only if π1π2 = β1.
12. 12
Example 5.67. Determine by means of slopes whether the points π΄ β3, β4 ,
π΅(2, β1) and πΆ(7, 2) are collinear.
Solution: Points are said to be collinear if they lie on the same line. Thus the
given points are collinear if we can show that the slope π1 of π΄π΅ and the slope
π2 of π΅πΆ are equal with π΅ as common point. Now,
π1 =
β1β(β4)
2β(β3)
=
3
5
and π2 =
2β(β1)
7β2
=
3
5
.
Since π1 = π2, it follows that the line through π΄ and π΅ and the line through π΅
and πΆ have the same slope and contain the common point π΅. Therefore the given
points π΄, π΅ and πΆ are collinear.
Example 5.68. Given the line π having the equation 5π₯ + 4π¦ β 20 = 0, find an
equation of the line through the point (2, β3) that is (a) parallel to π, and (b)
perpendicular to π.
13. 13
Solution: To visualize, we sketch the graph first.
-12 -10 -8 -6 -4 -2 2 4 6 8 10 12
-12
-8
-4
4
8
12
π₯
π¦
π(2, β3)
Solving for π₯ and π¦
intercepts of the linear
equation 5π₯ + 4π¦ β 20 = 0
we have,
π₯-intercept:
π¦ = 0 βΉ π₯ = 4
π¦-intercept:
π₯ = 0 βΉ π¦ = 5
5π₯ + 4π¦ β 20 = 0
Perpendicular line passing
through the point π(2, β3)
Parallel line passing
through the point π(2, β3)
14. 14
Solution:
First we need to get the slope of 5π₯ + 4π¦ β 20 = 0, that is
4π¦ = β5π₯ + 20
π¦ = β
5
4
π₯ + 5
which implies that the slope is π = β
5
4
. Let πβ₯ and πβ₯ be the slope of parallel
and perpendicular lines respectively. Then
(a) πβ₯ = β
5
4
and since the required line contains the point (2, β3), we use the
point-slope form which gives
π¦ + 3 = β
5
4
π₯ β 2 βΊ 5π₯ + 4π¦ + 2 = 0.
(b) πβ₯ =
4
5
and so we have
π¦ + 3 =
4
5
π₯ β 2 βΊ 4π₯ β 5π¦ β 23 = 0.
15. 15
Example 5.69. Prove that points π΄ 6, β13 , π΅ β2, 2 , πΆ(13, 10), and π·(21, β5)
are vertices of a square.
Solution:
-30 -25 -20 -15 -10 -5 5 10 15 20 25 30
-30
-20
-10
10
20
30
π₯
π¦
π΄ 6,β13
π΅ β2,2
πΆ(13, 10)
π·(21,β5)
To prove that points π΄, π΅, πΆ and π· are vertices of
a square, we need to show the following:
(i) π΄π΅ = π΄π· = π΅πΆ = πΆπ·
(ii) Let π1, π2, π3, and π4 be the respective
slope of π΄π΅, π΄π·, π΅πΆ, and πΆπ·, then show
that π1π2 = β1, π1π3 = β1,
π2π4 = β1, and π3π4 = β1.
π1
π2
π3
π4
17. 17
Therefore the given four points are vertices of a square.
Solving for a diagonal, we obtain
π΄πΆ = 13 β 6 2 + 10 β (β13) 2 = 17 2.
Example 5.70. Given the line π having the equation 2π¦ β 3π₯ β 4 = 0 and the
point π(1, β3), find (a) an equation of the line through π and perpendicular to π
and (b) the shortest distance from π to π.
Solution:
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
Let us first solve the π₯ and π¦ intercepts for the
given linear equation 2π¦ β 3π₯ = 4
π₯-intercept:
π¦ = 0 βΉ π₯ = β
4
3
π¦-intercept:
π₯ = 0 βΉ π¦ = 2
2π¦ β 3π₯ = 4
π(1,β3)
π(π₯, π¦)
19. 19
(b) To find the shortest distance we need to solve the point of intersection between
given line π which is 2π¦ β 3π₯ β 4 = 0 and the line perpendicular to π which is
2π₯ + 3π¦ + 7 = 0. Now solving for the values of π₯ and π¦ of the system below,
β3π₯ + 2π¦ = 4
2π₯ + 3π¦ = β7
we have π₯ = β2 and π¦ = β1, that is, π(β2, β1). Therefore the shortest distance
containing points π(1, β3) and π(β2, β1) is
ππ = β2 β 1 2 + β1 β (β3) 2 = 13 units.
20. 20
Example 5.71. If two vertices of an equilateral triangle are (β4, 3) and (0, 0), find
the third vertex.
Solution:
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
π₯
π΅(β4,3)
π΄(0, 0)
Let π΄(0, 0), π΅(β4, 3) and πΆ(π₯, π¦). Since we are
dealing with equilateral triangle, it follows that
π΄π΅ = π΅πΆ = π΄πΆ
27. 27
Therefore the third vertex of an equilateral triangle is either in first quadrant at the
point
πΆ β2 +
3
2
3,
3
2
+ 2 3
or in the third quadrant at the point
πΆ β2 β
3
2
3,
3
2
β 2 3
28. 28
Definition 5.72. The parabola is defined to be the set of all points in a plane equidistant from
the fixed point which is called the focus and the fixed line which is called the directrix. The
line through the focus perpendicular to the directrix is called the axis of the parabola.
The general/standard equation of the parabola which is either concave upward or
downward is of the form
(π₯ β β)2= 4π(π¦ β π)
which has the following properties:
(a) Vertex: π(β, π);
(b) when π > 0, the parabola concaves upward; otherwise concave downwards when π < 0;
(c) The location of the focus is at point πΉ(β, π + π);
(d) The Latus Rectum is the chord passes through the focus whose length is
πΏπ = 4π ;
(e) The equation of the directrix is π¦ = π β π.
(f) The equation of the axis is π₯ = β.
29. 29
Example 5.73. Let us draw a sketch of the parabola having an equation π₯2
β 4π₯ β 8π¦ β
28 = 0 and determine the properties (a)-(e) in the previous slide. The complete solution is
shown below.
π₯2
β 4π₯ β 8π¦ β 28 = 0
π₯2
β 4π₯ = 8π¦ + 28
π₯2 β 4π₯ +
β4
2
2
= 8π¦ + 28 + 4 (by completing the square method)
(π₯ β 2)2= 8π¦ + 32
(π₯ β 2)2= 8(π¦ + 4)
Thus,
(a) Vertex: π 2, β4 ;
(b) Concavity: 4π = 8 βΉ π = 2 > 0, parabola concaves upward;
(c) Focus: πΉ 2, β4 + 2 = πΉ(2, β2);
(d) Length of latus rectum: πΏπ = 8 = 8 with extreme points at πΈβ²(β2, β2) and πΈ(6, β2);
(e) Directix: π¦ = π β π βΉ π¦ = β4 β 2 = β6; and
(f) Axis: π₯ = 2.
33. 33
The general/standard equation of the parabola which is either concave to the
right or to the left is
(π¦ β π)2
= 4π(π₯ β β)
which has the following properties:
(a) Vertex: π(β, π);
(b) when π > 0, the parabola concaves to the right; otherwise concave to the
left when π < 0;
(c) The location of the focus is at point πΉ(β + π, π);
(d) The Latus Rectum is the chord passes through the focus whose length is
πΏπ = 4π ;
(e) The equation of the directrix is π₯ = β β π.
(f) Axis: π¦ = π
38. 38
Example 5.76 (Application). The cable of a suspension suspension bridge hangs in the form
of a parabola when the load is uniformly distributed horizontally. The distance between two
towers are 150 meters, the points of support of the cable on the towers are 22 meters above
the roadway, and the lowest point is 7 meters above the roadway. Find the vertical distance to
the cable from a point in the roadway 15 meters from the foot of a tower.
Solution:
π 0,7
0, 0
150 m
22 m
75 m
15 m
π2 60,π¦
π1 75,22
Apply: π₯ β β 2 = 4π(π¦ β π)
*π 0,7 : π₯ β 0 2
= 4π(π¦ β 7)
π₯2
= 4π(π¦ β 7)
*π1(75, 22): (75)2
= 4π(22 β 7)
4π = 375
*π2(60, π¦): (60)2= 375(π¦ β 7)
π¦ =
83
5
= 16.6
Therefore the vertical distance to the cable
from the point in the roadway 15 meters from
the foot of a tower is 16.6 meters.
39. 39
Example 5.77 (Application). A reflecting telescope has a parabolic mirror for which the
distance from the vertex to the focus is 30 feet. If the distance across the top of the mirror is
64 inches, how deep is the mirror at the center?
Solution:
π(32,π¦)
πΉ(0, 360)
(0,0)
30 ft
12 ππ
1ππ‘
= 360 ππ
Apply: π₯ β β 2 = 4π(π¦ β π)
* π(0, 0): π₯ β 0 2
= 4π(π¦ β 0)
π₯2
= 4ππ¦
* πΉ 0, 360 βΉ π = 360
* π(32, π¦): (32)2= 4(360)π¦
π¦ =
32
45
β 0.71 in
40. 40
Definition 5.78 (Circle). A circle is the set of all points in a plane equidistant from a fixed
point. The fixed point is called the center of the circle and the constant equal distance is
called the radius of the circle.
The general equation of the circle is
π₯2
+ π¦2
+ π·π₯ + πΈπ¦ + πΉ = 0
where π·, πΈ, and πΉ are constants which can be transformed in to
(π₯ β β)2
+(π¦ β π)2
= π2
of which the center is at the point πΆ(β, π) and the radius is π.
Example 5.79. Determine whether the graph is a circle, point, or the empty set.
a. π₯2
+ π¦2
+ 6π₯ β 2π¦ β 15 = 0
b. π₯2 + π¦2 β 4π₯ + 10π¦ + 29 = 0
c. π₯2
+ π¦2
+ 8π₯ β 6π¦ + 30 = 0
b. 4π₯2
+ 4π¦2
+ 24π₯ β 4π¦ + 1 = 0
We take note that after transforming is π₯2 + π¦2 + π·π₯ + πΈπ¦ + πΉ = 0 in to
(π₯ β β)2+(π¦ β π)2= π2 and if π = 0, then the graph is a point; otherwise an empty set if π is
negative.
42. 42
Graph
-12 -10 -8 -6 -4 -2 2 4 6 8 10 12
-12
-8
-4
4,
8
12
x
y
πΆ β3,1 2,1
β8,1
β3,6
β3,β4
Therefore the center is at πΆ β3,
1
2
with radius π = 3 units where the graph is shown below.
Note:
* Not a function
* Domain= [β8,2]
* Range= β4,6
43. 43
(b) π₯2
+ π¦2
β 4π₯ + 10π¦ + 29 = 0
π₯2
β 4π₯ + π¦2
+ 10π¦ = β29
π₯2 β 4π₯ + β
4
2
2
+ π¦2 + 10π¦ +
10
2
2
= β29 + 4 + 25
(by completing the square method)
π₯ β 2 2 + π¦ + 5 2 = 0
Hence πΆ(2, β5) and observe that π = 0 implies that the graph is a point as shown
in the next slide.
47. 47
Graph
-6 -5 -4 -3 -2 -1 1 2 3 4 5 6
-6
-4
-2
2
4
6
x
y
πΆ β3,
1
2 0,
1
2
β6,
1
2
β3,
7
2
β3, β
5
2
Therefore the center is at πΆ β3,
1
2
with radius π = 3 units where the graph is shown below.
Note:
* Not a function
* Domain= [β6,0]
* Range= β
5
2
,
7
2
48. 48
Definition 5.79 (Ellipse). An ellipse is the set of points in a plane, the sum of
whose distances from the two fixed points is a constant. Each fixed point is called a
focus.
The general equation of an ellipse is
π₯ββ 2
π2 +
π¦βπ 2
π2 = 1.
(a) π > π βΉPrincipal axis (P.A.) is
horizontal and minor axis (M.A.) is
vertical;
π > π βΉPrincipal axis (P.A.) is vertical
and minor axis (M.A.) is horizontal;
(b) The center is at πΆ(β, π) and the
equation of the principal axis is π¦ = π.
Center: πΆ(β, π) and the equation of the
principal axis is π₯ = β.
Let us tabulate some informations on ellipse or to compare where the
principal axis is either horizontal or vertical.
49. 49
(c) Let us label the vertices of P.A. and
extremities of M.A. by the following:
Vertices of P.A.:
π1 β β π, π and π2 β + π, π ;
Extremities of M.A.:
πΈ1 β, π + π and πΈ2(β, π β π).
Vertices of P.A.:
π1 β, π + π and π2(β, π β π);
Extremities of M.A.:
πΈ1 β β π, π and πΈ2 β + π, π .
(d) Location of the Foci:
πΉ1(β β π, π), πΉ2(β + π, π)
where solving for the value of π, we use
π2 = π2 β π2.
Location of the Foci:
πΉ1(β, π + π), πΉ2(β, π β π)
where solving for the value of π we use
the formula
π2
= π2
β π2
.
(e) Distance between the foci:
πΉ1πΉ2 = 2π
πΉ1πΉ2 = 2π
50. 50
(f) Distance between the vertices in the
P.A.:
π1π2 = 2π
π1π2 = 2π
(g) From the definition of an ellipse we
see that it is the set of points in a plane,
the sum of whose distances from the
two fixed points is a constant, so we
must have
πΉ1π + πΉ2π = 2π
where point π(π₯, π¦) is any point on the
graph of an ellipse.
πΉ1π + πΉ2π = 2π
51. 51
Example 5.80. Let us label all the parts of the graph of an ellipse (by using the
information tabulated above) having and equation
6π₯2
+ 9π¦2
β 24π₯ β 54π¦ + 51 = 0.
Converting 6π₯2
+ 9π¦2
β 24π₯ β 54π¦ + 51 = 0 into
π₯ββ 2
π2 +
π¦βπ 2
π2 = 1, we have
6π₯2 + 9π¦2 β 24π₯ β 54π¦ + 51 = 0
6π₯2 β 24π₯ + 9π¦2 β 54π¦ = β51
6 π₯2 β 4π₯ + 9 π¦2 β 6π¦ = β51
6 π₯2 β 4π₯ + β
4
2
+ 9 π¦2 β 6π¦ + β
6
2
= β51
6 π₯ β 2 2
+ 9 π¦ β 3 2
= β51 + 24 + 81
52. 52
6 π₯ β 2 2 + 9 π¦ β 3 2 = 54
1
54
π₯ β 2 2
9
+
π¦ β 3 2
6
= 1
π₯ β 2 2
32 +
π¦ β 3 2
6
2 = 1
Thus, π = 3 and π = 6 and so to verify the facts about an ellipse which are
listed in the table above, we have
(a) π = 3 > π = 6 βΉPrincipal axis (P.A.) is horizontal and minor axis (M.A.)
is vertical;
53. 53
(b) Center: πΆ β, π = πΆ(2, 3) and the equation of the principal axis is π¦ = 3;
(c) Vertices of P.A.: π1 2 β 3, 3 = π1 β1, 3 and π2 2 + 3, 3 = π2 5, 3 ;
Extremities of M.A.: πΈ1 2, 3 + 6 and πΈ2 2, 3 β 6 ;
(d) The foci are located at πΉ1 2 β 3, 3 and πΉ2(2 + 3, 3) because
π2
= 9 β 6 βΉ π = 3;
(e) Distance between the foci: πΉ1πΉ2 = 2 β 3 β 2 + 3
2
+ 3 β 3 2
= β2 3
2
+ 0 2
= β2 3
= 2 3
= 2π;
54. 54
(f) Distance between the vertices in the P.A.:
π1π2 = β1 β 5 2 + 3 β 3 2
= β6 2 + 0 2
= β6
= 6
= 2(3)
= 2π;
55. 55
(g) From the definition of an ellipse we see that it is the set of points in a plane, the
sum of whose distances from the two fixed points is a constant, so we must
have πΉ1π + πΉ2π = 2π. Now, take the point π π₯, π¦ = πΈ1 2, 3 + 6 and so
πΉ1π + πΉ2π
= 2 + 3 β 2
2
+ 3 β 3 + 6
2
+ 2 β 2 β 3
2
+ 3 + 6 β 3
2
= 3
2
+ 6
2
+ 3
2
+ 6
2
= 9 + 9
= 3 + 3
= 6
= 2(3)
= 2π.
57. 57
Example 5.81. Similarly let us label all the parts of the graph of an ellipse (by
using the information tabulated above) having and equation
4π₯2
+ π¦2
+ 8π₯ β 4π¦ β 92 = 0.
Determining the important parts and verify the formulas in the table above, we
have
4π₯2
+ π¦2
+ 8π₯ β 4π¦ β 92 = 0
4π₯2 + 8π₯ + π¦2 β 4π¦ = 92
4 π₯2
+ 2π₯ +
2
2
2
+ π¦2
β 4π¦ + β
4
2
2
= 92 + 4 + 4
4 π₯ + 1 2 + π₯ β 2 2 = 100
1
100
58. 58
π₯ + 1 2
25
+
π₯ β 2 2
100
= 1
π₯ + 1 2
52
+
π₯ β 2 2
102
= 1
Therefore,
(a) π = 5 < π = 10 βΉPrincipal axis (P.A.) is vertical and minor axis (M.A.) is
horizontal;
(b) Center: πΆ(β1, 2) and the equation of the principal axis is π₯ = β1;
(c) Vertices of P.A.:
π1 β1, 2 + 10 = π1 β1, 12 and π2 β1, 2 β 10 = π2 β1, β8 ;
Extremities of M.A.: πΈ1 β1 β 5, 2 = πΈ1 β6, 2 and πΈ2 4, 2 ;
63. 63
Definition 5.80 (Hyperbola). A hyperbola is the set of points in a plane, the absolute value
of the difference of whose distances from the two fixed points is a constant. The two fixed
points are called the foci.
The general equation of the hyperbola is
π₯ββ 2
π2 β
π¦βπ 2
π2 = 1.
Note:
1. The line through the foci is called the principal axis of the hyperbola.
2. The points where the graphs intersects the principal axis are called the vertices.
3. If the principal axis is horizontal, then the equation of the hyperbola is
π₯ β β 2
π2 β
π¦ β π 2
π2 = 1
where the:
(a) center πΆ(β, π) is the midpoint between the vertices;
64. 64
(b) vertices are located at π1(β β π, π) and π2(β + π, π) an;
(c) line segment joining the vertices is called the transverse axis and its
length is π»π¨ = π1π2 = ππ units.
(d) line segment having extremities at πΈ1(β, π + π) and πΈ2(β, π β π) is called
the conjugate axis;
(e) length of conjugate axis is πͺπ¨ = πΈ1πΈ2 = ππ units;
(f) foci are located at πΉ1(β β π, π) and πΉ2(β + π, π) where π2
= π2
+ π2
;
(g) πΉ1π β πΉ2π = 2π where point π(π₯, π¦) is any point on the hyperbola;
(h) equation of the asymptotes
π₯ββ 2
π2 β
π¦βπ 2
π2 0.
65. 65
4. If the principal axis is vertical, then the equation of the hyperbola is
β
π₯ β β 2
π2
+
π¦ β π 2
π2
= 1
where the:
(a) center πΆ(β, π) is the midpoint between the vertices;
(b) vertices are located at π1(β, π + π) and π2(β, π β π);
(c) line segment joining the vertices is called the transverse axis and its
length is π»π¨ = π1π2 = ππ units.
(d) line segment having extremities at πΈ1(β β π, π) and πΈ2(β + π, π) is called
the conjugate axis;
(e) and its length is πͺπ¨ = πΈ1πΈ2 = ππ units;
(f) foci are located at πΉ1(β, π + π) and πΉ2(β, π β π) where π2 = π2 + π2;
(g) πΉ1π β πΉ2π = 2π where point π(π₯, π¦) is any point on the hyperbola; and
(h) equation of the asymptotes
β
π₯ββ 2
π2 +
π¦βπ 2
π2 0.
70. 70
Example 5.82. Sketch the graph of 9π₯2
β 18π¦2
+ 54π₯ β 36π¦ + 79 = 0 and label
its parts as listed in the previous slide.
The solution will be discuss during google class meeting!
75. 75
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Precalculus 7th Edition. McGraw-Hill, c 2011
[2] Hart, William L. Plane and Spherical Trigonometry. Boston: D.C. Heath and
Company, c1964
[3] Johnson, Richard E., et. al. Algebra and Trigonometry 2nd edition. California:
Addison β Wesley Publishing Company, c1971
[4] Leithold, Louis College Algebra and Trigonometry. Massachusetts: Addison β
Wesley Publishing Company, c1989
[5] Miller, Charles D. Fundamentals of College Algebra. New York: Harper
Collins College Publishers, c1994
[6] Robinson N. Elements of Plane and Spherical Trigonometry. American Book
Company, c1970
[7]Spiegel, Murray, Moyer Robert E. College Algebra. New York. McGraw β
Hill, c1998
76. 76
[8] Sullivan, Michael. Trigonometry: A Unit Circle Approach. Prentice Hall, c
2012
[9] Vance, Elbridge P. Modern Algebra and Trigonometry. Massachusetts:
Addison β Wesley Publishing Company, c1975