# Law of Cosines

**Definition : **

In trigonometry, the law of cosines is also referred to as cosine law, Cos formula, or cosine rule. It is defined as the equation relating to the length of the sides of a triangle to the cosines of its angles. It is the ratio of the length of the adjacent side to the length of the hypotenuse. The below given calculator assists you in calculating the value of cosine function from the known adjacent and hypotenuse values.

#### Cosine Rule Calculator

### Formula :

cos (α)

= Adjacent Side / Hypotenuse