# A triangle has sides A, B, and C. Sides A and B are of lengths #2# and #1#, respectively, and the angle between A and B is #pi/3#. What is the length of side C?

##### 1 Answer

May 1, 2018

#### Explanation:

When you have the lengths of two sides of a triangle and the angle between, then you can solve the missing side with the **law of cosines**.

We want side

Let's substitute in the values and solve:

Now simplify:

You can leave it like that, but if you want the answer to be in decimal form, it is

Hope this helps!