Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
This article is about the cross-section of the sphere. For other uses, see Secant (disambiguation).
Animation showing the circular secant planes of the ellipsoid
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.
Applications
Comparison of tangent and secant cylindrical, conic and azimuthal map projections with standard parallels shown in red
Secant planes are used in map projections. The secant plane intersects a globe along a small circle with no distortion, forming a standard parallel which has true scale.
