Law of Cosines

What it is, When to use it, and How to use it!


where a and b are the given sides

C is the included angle

c is the unknown third side

When do you use it?

When you know two sides and an angle, it also works on any triangle.


side a: 23.6

side b: 8.2

side c: unknown

angle c: 60 degrees

Try it!

side a: 11.1

side b: 15.3

side c: unknown

angle c: 15