# Cosine Function

## Cosine Function

In a trigonometric circle, function f of $$\mathbb{R}$$ in $$\mathbb{R}$$ in which all angles of rotation x are made to correspond to the x-coordinate of a point P of the circle.

In the illustration above, cos(x) = h, which is the x-coordinate of point P.

### Notation

The cosine function is noted as “cos” and the image of an angle of rotation x by this function is written as “cos(x)” and is read as “cosine x” or “cosine of x.”

### Example

Here is the representation of the basic function defined by the relation f (x) = cos(x):