Conics

Conics

A conic section is any curve produced by the intersection of a plane and a right circular cone. Depending on the angle of the plane relative to the cone, the intersection is a circle, an ellipse, a hyperbola, or a parabola.
Special cases of intersection are that of the plane passing through the apex and no other part of the cone, in which a single point is produced, and that of the plane passing through the apex intersecting the cone elsewhere, in which one or two intersecting lines are produced. [RA] {EB}