Definition:Secant Line

Definition
Let $f: \R \to \R$ be a real function.

Let the graph of $f$ be depicted on a Cartesian plane.


 * SecantToCurve.png

A secant to $f$ is a straight line which intersects the graph of $f$ in (at least) two points.

In the above diagram, the secant is the line $AB$ in $\color {blue} {\text {blue} }$.