# What is the law of cosines?

##### 1 Answer

Dec 21, 2014

Cosider the triangle:

(Picture source: Wikipedia)

you can relate the sides of this triangle in a kind of "extended" form of Pitagora's Theorem giving:

As you can see you use this law when your triangle is not a right-angled one.

Example:

Consider the above triangle in which:

so: