Since the directrix is vertical, use the equation of a parabola that opens up or down.
Find the vertex.
The vertex is halfway between the directrix and focus. Find the coordinate of the vertex using the formula . The coordinate will be the same as the coordinate of the focus.
Simplify the vertex.
Add and .
Divide by .
Find the distance from the focus to the vertex.
The distance from the focus to the vertex and from the vertex to the directrix is . Subtract the coordinate of the vertex from the coordinate of the focus to find .
Subtract from .
Substitute in the known values for the variables into the equation .
Find the Parabola with Focus (0,-5) and Directrix y=5 (0,-5) y=5