Secant line
= Secant line
A <secant line> is a <straight line> passing through two distinct points of a <curve>. For a graph $y=f(x)$ at $x=a$ and $x=a+h$, its <slope> is the <difference quotient> $(f(a+h)-f(a))/h$. As the second point approaches the first, a limiting <secant line> can give the <tangent line>.