Ahyperbola 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