Part B Find the equation of the directrix of the parabola found in part A.

Part A
A manufacturer is designing a flashlight. For the flashlight to emit a focused beam, the bulb needs to be on the central axis of the parabolic reflector, 3 centimeters from the vertex. Write an equation that models the parabola formed when a cross section is taken through the reflector’s central axis. Assume that the vertex of the parabola is at the origin in the xy coordinate plane and the parabola can open in any direction.
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y= 1/12(x-0)^2+0

To solve you need to use a veritcal parabola is y=1/4p(x-h)^2+k
The coordinates are h, and k for the vertex of the parabola
p is the absolute value of the distance from the vertex to the focus/directrix
The vertex is is at the origin (0,0) and the focus bulb is 3 cebtuneters away from the vertex
Now that we know the values we can fill them in
1/4p turns into 1/12 since p is 3
(x-h)^2+k turns into (x-0)^2+0, since h and k where the values of the vertex which was 0,0
All the variables were given, and we now have our equation