Editing Sphere (section)

===Spherical conics===
{{Main|Spherical conic}}
The analog of a [[conic section]] on the sphere is a [[spherical conic]], a [[quartic function|quartic]] curve which can be defined in several equivalent ways.
*The intersection of a sphere with a quadratic cone whose vertex is the sphere center
*The intersection of a sphere with an [[cylinder#cylindrical surfaces|elliptic or hyperbolic cylinder]] whose axis passes through the sphere center
*The locus of points whose sum or difference of [[great-circle distance]]s from a pair of [[focus (geometry)|foci]] is a constant

Many theorems relating to planar conic sections also extend to spherical conics.