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8.2 The Hyperbola
Chapter 8 Analytic Geometry
Concepts and Objectives
 The objectives for this section are
 Locate a hyperbolas vertices and foci.
 Write equations of hyperbolas in standard form.
 Graph hyperbolas centered at the origin.
 Graph hyperbolas not centered at the origin.
 Solve applied problems involving hyperbolas.
Hyperbolas
 Hyperbolas have two disconnected branches. Each
branch approaches diagonal asymptotes.
 Parts of a hyperbola:
 Center
 Vertices
 Asymptotes
 Hyperbola
Hyperbolas
 The general equation of a hyperbola is
or
 The hyperbola opens in whichever direction has the
positive term (x-direction if x is positive, y-direction if y
is positive).
 The slope of the asymptotes is always .
 The vertices are rx or ry from the center, whichever
term is positive. a is the positive term radius, b is the
negative term radius.
 
 
 
 =
 
   
   
2
2
1
x y
x h y k
r r
 
 
 
 + =
 
   
   
2
2
1
x y
x h y k
r r
 y
x
r
r
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( ) ( ) ( )
+
+  =
+ +

 
2
2 2 2
2 2
9 10 8 197
5 9 5
4 4 4 4
x x y y
Notice that the
negative sign has
been factored as
well!
Remember to
distribute the
negative sign!
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( ) ( ) ( )
+
+  =
+ +

 
2
2 2 2
2 2
9 10 8 197
5 9 5
4 4 4 4
x x y y
( ) ( )
+   = 
2 2
9 6
4 4
5 3
x y
Notice that the
negative sign has
been factored as
well!
Remember to
distribute the
negative sign!
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( ) ( ) ( )
+
+  =
+ +

 
2
2 2 2
2 2
9 10 8 197
5 9 5
4 4 4 4
x x y y
( ) ( )
+  
 =
  
2 2
9 5 4 4 36
36 36 36
x y
Notice that the
negative sign has
been factored as
well!
Remember to
distribute the
negative sign!
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( ) ( ) ( )
+
+  =
+ +

 
2
2 2 2
2 2
9 10 8 197
5 9 5
4 4 4 4
x x y y
( ) ( )
+  
 =
  
2 2
9 5 4 4 36
36 36 36
x y
( ) ( )
+ 
 + =
2 2
5 4
1
4 9
x y
Notice that the
negative sign has
been factored as
well!
Remember to
distribute the
negative sign!
Hyperbolas
 Example: Graph  + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( ) ( ) ( )
+
+  =
+ +

 
2
2 2 2
2 2
9 10 8 197
5 9 5
4 4 4 4
x x y y
( ) ( )
+  
 =
  
2 2
9 5 4 4 36
36 36 36
x y
( ) ( )
+ 
 + =
2 2
5 4
1
4 9
x y
( ) ( )
+ 
 + =
2 2
2 2
5 4
1
2 3
x y
Notice that the
negative sign has
been factored as
well!
Remember to
distribute the
negative sign!
Hyperbolas
 Example: Graph
Center (5, 4)
 + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( )
+ 
 + =
2 2
2 2
5 4
1
2 3
x y
Hyperbolas
 Example: Graph
Center (5, 4)
opens in y-direction
rx = 2, ry = 3
 vertices 3
 + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( )
+ 
 + =
2 2
2 2
5 4
1
2 3
x y
Hyperbolas
 Example: Graph
Center (5, 4)
opens in y-direction
rx = 2, ry = 3
 vertices 3
slope of asymptotes:
 + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( )
+ 
 + =
2 2
2 2
5 4
1
2 3
x y

3
2
Hyperbolas
 Example: Graph
Center (5, 4)
opens in y-direction
rx = 2, ry = 3
 vertices 3
slope of asymptotes:
 + + + =
2 2
9 4 90 32 197 0
x y x y
( ) ( )
+ 
 + =
2 2
2 2
5 4
1
2 3
x y

3
2
Focal Length
 In an ellipse, the sum of the distances from a point on the
ellipse to the two foci is constant, but in a hyperbola, its
the difference between the distances that is constant.
 To find the focal radius, we can use the Pythagorean
Theorem.
 Notice that c > a for the
hyperbola. a
b
c

= +
2 2 2
c a b
Classwork
 College Algebra 2e
 8.2: 12-44 (4); 8.1: 32-56 (4); 7.8: 36-44 (4)
 8.2 Classwork Check
 Quiz 8.1

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8.2 The Hyperbola

  • 1. 8.2 The Hyperbola Chapter 8 Analytic Geometry
  • 2. Concepts and Objectives The objectives for this section are Locate a hyperbolas vertices and foci. Write equations of hyperbolas in standard form. Graph hyperbolas centered at the origin. Graph hyperbolas not centered at the origin. Solve applied problems involving hyperbolas.
  • 3. Hyperbolas Hyperbolas have two disconnected branches. Each branch approaches diagonal asymptotes. Parts of a hyperbola: Center Vertices Asymptotes Hyperbola
  • 4. Hyperbolas The general equation of a hyperbola is or The hyperbola opens in whichever direction has the positive term (x-direction if x is positive, y-direction if y is positive). The slope of the asymptotes is always . The vertices are rx or ry from the center, whichever term is positive. a is the positive term radius, b is the negative term radius. = 2 2 1 x y x h y k r r + = 2 2 1 x y x h y k r r y x r r
  • 5. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y
  • 6. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) ( ) ( ) + + = + + 2 2 2 2 2 2 9 10 8 197 5 9 5 4 4 4 4 x x y y Notice that the negative sign has been factored as well! Remember to distribute the negative sign!
  • 7. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) ( ) ( ) + + = + + 2 2 2 2 2 2 9 10 8 197 5 9 5 4 4 4 4 x x y y ( ) ( ) + = 2 2 9 6 4 4 5 3 x y Notice that the negative sign has been factored as well! Remember to distribute the negative sign!
  • 8. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) ( ) ( ) + + = + + 2 2 2 2 2 2 9 10 8 197 5 9 5 4 4 4 4 x x y y ( ) ( ) + = 2 2 9 5 4 4 36 36 36 36 x y Notice that the negative sign has been factored as well! Remember to distribute the negative sign!
  • 9. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) ( ) ( ) + + = + + 2 2 2 2 2 2 9 10 8 197 5 9 5 4 4 4 4 x x y y ( ) ( ) + = 2 2 9 5 4 4 36 36 36 36 x y ( ) ( ) + + = 2 2 5 4 1 4 9 x y Notice that the negative sign has been factored as well! Remember to distribute the negative sign!
  • 10. Hyperbolas Example: Graph + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) ( ) ( ) + + = + + 2 2 2 2 2 2 9 10 8 197 5 9 5 4 4 4 4 x x y y ( ) ( ) + = 2 2 9 5 4 4 36 36 36 36 x y ( ) ( ) + + = 2 2 5 4 1 4 9 x y ( ) ( ) + + = 2 2 2 2 5 4 1 2 3 x y Notice that the negative sign has been factored as well! Remember to distribute the negative sign!
  • 11. Hyperbolas Example: Graph Center (5, 4) + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) + + = 2 2 2 2 5 4 1 2 3 x y
  • 12. Hyperbolas Example: Graph Center (5, 4) opens in y-direction rx = 2, ry = 3 vertices 3 + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) + + = 2 2 2 2 5 4 1 2 3 x y
  • 13. Hyperbolas Example: Graph Center (5, 4) opens in y-direction rx = 2, ry = 3 vertices 3 slope of asymptotes: + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) + + = 2 2 2 2 5 4 1 2 3 x y 3 2
  • 14. Hyperbolas Example: Graph Center (5, 4) opens in y-direction rx = 2, ry = 3 vertices 3 slope of asymptotes: + + + = 2 2 9 4 90 32 197 0 x y x y ( ) ( ) + + = 2 2 2 2 5 4 1 2 3 x y 3 2
  • 15. Focal Length In an ellipse, the sum of the distances from a point on the ellipse to the two foci is constant, but in a hyperbola, its the difference between the distances that is constant. To find the focal radius, we can use the Pythagorean Theorem. Notice that c > a for the hyperbola. a b c = + 2 2 2 c a b
  • 16. Classwork College Algebra 2e 8.2: 12-44 (4); 8.1: 32-56 (4); 7.8: 36-44 (4) 8.2 Classwork Check Quiz 8.1