McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
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Exercise 48 Page 649

The equation of a vertical hyperbola is (y-k)^2a^2- (x-h)^2b^2=1. The vertices are (h,k ± a). How can you find the foci and the asymptotes?

Vertices: (4,3) and (4,- 5)
Foci: (4,4) and (4,- 6)
Asymptotes: y=± 4/3(x-4)-1
Graph:

Practice makes perfect

We will find the desired information, and use it to draw the graph of the hyperbola.

Vertices, Foci, and Asymptotes

Let's start by recalling the equation of hyperbolas centered at (h,k). Horizontal Hyperbola (x-h)^2/a^2-(y-k)^2/b^2=1 Vertical Hyperbola (y-k)^2/a^2-(x-h)^2/b^2=1 Now we will rewrite the given equation to match one of these formats.

(y+1)^2/16-(x-4)^2/9=1
â–¼
Simplify left-hand side

a=- (- a)

(y-(- 1))^2/16-(x-4)^2/9=1
(y-(- 1))^2/4^2-(x-4)^2/3^2=1

From the above formula, we can see that the equation represents a vertical hyperbola. Next, let's review the main characteristics of this type of hyperbola.

Vertical Hyperbola with Center (h,k)
Equation (y-k)^2/a^2-(x-h)^2/b^2=1
Transverse axis Vertical
Vertices (h ,k± a)
Foci (h ,k± c), where c^2=a^2+b^2
Asymptotes y-k=± a/b(x-h)

Using this information, we can identify that the center of the hyperbola is (4,- 1). The vertices we find using the formula (h ,k± a). (4, - 1+4)=(4,3) [0.6em] (4,- 1-4)=(4,- 5) Let's substitute h=4, k=- 1, a=4, and b=3 into the formula for the asymptotes and obtain their equations.

y-k=± a/b(x-h)
y-(- 1)=± 4/3(x-4)
â–¼
Simplify
y+1=± 4/3(x-4)
y+1=± 4/3(x-4)
y=± 4/3(x-4)-1

The asymptotes are y=± 4/3(x-4)-1. Now, let's calculate c. To do so, we will substitute a=4 and b=3 into c^2=a^2+b^2.

c^2=a^2+b^2
c^2=4^2+3^2
â–¼
Solve for c
c^2=16+9
c^2=25
c=± 5

We can now use the formula (h ,k± c) to find the foci of the hyperbola. (4, - 1+ 5)=(4,4) [0.6em] (4,- 1- 5)=(4,- 6)

Graph

To graph the function, let's summarize all of the information that we have found.

Equation (y-(- 1))^2/4^2-(x-4)^2/3^2=1
Transverse axis Vertical
Vertices (4, 3) and (4, - 5)
Foci (4, 4) and (4, - 6)
Asymptotes y=± 4/3(x-4)-1

Finally, we can graph our hyperbola with center (4,-1).