# Law of Cosines

Written by Jerry Ratzlaff on . Posted in Trigonometry

An equation relating to cosine of an interior angle and the lengths of the sides of a triangle.

### Law of Cosines Formula

$$\large{ c^2= a^2+b^2-2ab* cosC }$$

$$\large{ a^2= b^2+c^2-2ab* cosA }$$

$$\large{ b^2= a^2+c^2-2ab* cosB }$$