Trigonometry is the study of angles and triangles, relying heavily on three basic functions: sine, cosine and tangent, and their inverses, Cotangent (Cot), Secant (sec) and Cosecant (csc). These functions are abbreviated as "sin", "cos" and "tan".
These functions are defined by reference to a "right triangle," which is a triangle in which one angle is 90 degrees.
- SOH: Sine = opposite over hypotenuse
- CAH: Cosine = adjacent over hypotenuse
- TOA: Tangent = opposite over adjacent
Pythagorean trigonometric identity: