Question

A hyperbola centered at the origin has a vertex at (0, 36) and a focus at (0, 39)

Which are the equations of the directrices ?

A. x= ±12/13
B. y=±12/13
C. x=±432/13
D. y=± 432/13

Answer 1

D. y=± 432/13

Explanation:

Answer 2

To solve this problem you must apply the proccedure shown below:

1. The vertex i at (0, 36) and a focus at (0, 39), then you have:

a=36
a^2=1296

2. The directrix is:

y=a^2=c
c=39
y=1296/39
y=432/13

Therefore, the answer is the option D, which is: D. y=± 432/13