A secant plane is a plane containing a nontrivial section of a sphere or an ellipsoid, or such a plane that a sphere is projected onto. Secant planes are similar to tangent planes, which contact the sphere's surface at a point, while secant planes contact the surface along curves.
The two-dimensional representations of secant planes are secant lines, the lines that join two distinct points on a curve.
- "Map projection - types and distortion". geokov.com. Retrieved 2016-11-02.