Definitions [3]
A parabola is the set of all points in a plane that are equidistant from a fixed line and a fixed point (not on the line) in the plane.
An ellipse is the set of all points in a plane, the sum of whose distances from two fixed points in the plane is a constant.
A hyperbola is the set of all points in a plane, the difference of whose distances from two fixed points in the plane is a constant.
