Tangent Line

A straight line is tangent to a given curve $f(x)$ at a point $x_0$ on the curve if the line passes through the point $(x_0,f(x_0))$ on the curve and has slope $f'(x_0)$, where $f'(x)$ is the Derivative of $f(x)$.

See also Circle Tangents, Secant Line, Tangent, Tangent Plane, Tangent Space, Tangent Vector

References

Yates, R. C. ``Instantaneous Center of Rotation and the Construction of Some Tangents.'' A Handbook on Curves and Their Properties. Ann Arbor, MI: J. W. Edwards, pp. 119-122, 1952.