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

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