Definitions for "Trigonometric functions"
Functions that perform trigonometric operations, such as cosine, sine, and tangent.
The ratios between sides of a triangle: sine {sin} (the side opposite the angle over the hypotenuse), cosine {cos} (the side adjacent to the angle over the hypotenuse), and tangent {tan} (opposite over adjacent); and their inverses: secant {sec} (hypotenuse over opposite), cosecant {cosec} (hypotenuse over adjacent), and cotangent {cot} (adjacent over opposite). (See Construction and Use of a Sundial and Observations Using a Gnomon)
A function (sine, cosine, tangent, cotangent, secant, cosecant) whose independent variable is an angle measure, usually in degrees or radians.