Find the standard form of the equation of the parabola with a focus at (0, 4) and a directrix at y = -4.

Question

anonymous · Answer

for the parabola 
x^2 = 4by
the focus is (0,b ) and the directrix is y=-b
can you do the above question now

anonymous · Answer

uuummm can you show me what the first step would be?

anonymous · Answer

compare your focus (0,4) with (0,b)  then can you make out 'b'

anonymous · Answer

oh so the answer is y2 = 16x ?

anonymous · Answer

if you get b =4 
then you need to replace 'b' by 4 in x^2 = 4by

anonymous · Answer

no 
x^2 = 16 y

imstuck · Answer

if i were you i would plot your points.  The focus is at (0,4) and you directrix is y = -4.  plotting them looks like this:

imstuck · Answer

|dw:1405749394926:dw|

imstuck · Answer

your vertex is exactly halfway between those two, like this:

imstuck · Answer

|dw:1405749472558:dw|