# Cosine function

## Description

The trigonometric functions (also called the circular functions) are functions of an angle. They relate the angles of a triangle to the lengths of its sides. The most familiar trigonometric functions are the sine, cosine, and tangent. To define the trigonometric functions for an angle , start with any right triangle that contains this angle . The three sides of the triangle are named: 1) hypotenuse (is the side opposite the right angle and always the longest side of the right-angled triangle).

2) opposite side (is the side opposite to the angle we are interested in)

3) adjacent side (Is the side having both the angles of interest ).

The cosine is defined as the ratio of the side adjacent an angle of a right angled triangle to it’s hypotenuse.

## Variables

ϕ | Angle (radian) |

b | Length of adjacent side (m) |

h | Length of hypotenuse (m) |