Geometry & Trigonometry
Basic

Cofunction Identity

Sine and cosine of complementary angles are equal.

Formula

sin⁡θ=cos⁡(90°−θ)\sin\theta = \cos(90\degree - \theta)

Variables

\thetaAngle

Example

sin30°=cos60°

Did You Know?

Sine and cosine are cofunctions because the sine of an angle equals the cosine of its complement — hence the "co".

trigidentity