# Secant Line

A secant line, also simply called a secant, is a line passing through two points of a curve. As the two points are brought together (or, more precisely, as one is brought towards the other), the secant line tends to a tangent line. In abstract mathematics, the points connected by a secant line can be eitherreal or complex conjugate imaginary.
In geometry, a secant line commonly refers to a line that intersects a circle at exactly two points (Rhoad et al. 1984, p. 429). There are a number of interesting theorems related to secant lines.

In the left figure above,
while in the right figure,
where  denotes the angular measure of the arc