Standard Equations for Conic Sections

Circle :

h = x coordinate at center
k = y coordinate at center
r = radius
Parabola :

h = x coordinate at center
k = y coordinate at center
p = distance from focus to directrix

Ellipse:

h = x coordinate at center
k = y coordinate at center
a = distance of major axis
b = distance of minor axis

Hyperbola:

h = x coordinate at center
k = y coordinate at center
a = distance of major axis
b = distance of minor axis