Ahyperbola centered at the origin has a vertex at (0, 36) and a focus at (0, 39). which are the equations of the directrices? x = ±12/13 y = ±12/13 x = ± 432/13 y = ±432/13

To solve this problem you must apply the proccedure shown below:
 1. You have that the hyperbola has a vertex at (0,36) and a focus at (0,39).
 2. Therefore, the equation of the directrices is:

 a=36
 a^2=1296
 c=39

 y=a^2/c

 3. When you susbtitute the values of a^2 and c into y=a^2/c, you obtain:

 y=a^2/c
 y=1296/13

 4. When you simplify:

 y=432/13

 Therefore, the answer is: y = ±432/13