# Cosine Function

Cosine takes in the angle of a right triangle as input and returns the ratio of the triangle’s adjacent side over its hypotenuse. The angle is represented by the symbol theta (θ). Illustrated below is the graph for the function cos(θ), from 0 to 2π. For each angle the corresponding right triangle of hypotenuse one is displayed on the left. Drag either of the points to interact with the visual.

## Examples

cos(0) = 1
cos(π/2) = 0
cos(π) = -1
cos(3π/2) = 0