A parabola that has a horizontal directrix is a parabola that opens up or down.
Here are some of its components:
1) Standard equation of a parabola with a horizontal directrix: (x-h)^2 = 4a(y-k),
a = distance from vertex to focus
2) Vertex at (h,k)
3) Focus(h,k+a)
4) Directrix: y = k-a
5) Axis of symmetry: x = h
A parabola that has a vertical directrix opens to the right or left and is on its side.
Here are some components
1) Standard equation of a parabola with a vertical directrix: (y-k)^2 = 4a(x-h)
2) vertex (h,k)
3) focus (h+a,k)
4) directrix: x = h-a
5) Axis of symmetry: y = k
Hopes this helps :)
