# Trigonometry - (Sine|Sinus)

Sine is the function of an angle (trigonometric function).

The word comes from the Latin sinus for gulf or bay, since, given a unit circle, it is the side of the triangle on which the angle opens.

## Derivative

For the sine function: $$f(x) = \sin x$$ The derivative is the cosine: $$f'(x) = \cos x$$