Name sometimes given to certain real functions such as trigonometric functions to relate them to one another.

### Example

Because sin(*a*) = cos(\(\frac{π}{2}\) – *a*), the sine function is the cofunction of the cosine function, and vice versa.

Name sometimes given to certain real functions such as trigonometric functions to relate them to one another.

Because sin(*a*) = cos(\(\frac{π}{2}\) – *a*), the sine function is the cofunction of the cosine function, and vice versa.