Law of Cosines
The law of cosines is a formula that relates the three sides of a triangle to the cosines of a given angle. This formula allows us to calculate the side length of non-right triangle as long as you know two sides and an angle and to calculate any angle of a triangle if you know all three side lengths.
The two common problems types that are suitable for the law of cosines are.
Problem type 1: when you know the lengths of 2 sides of a triangle and the angle in between the two sides Problem type 2: when you know the lengths of three sides of a triangle and want to know a particular angle
Learn more about law of cosines below.
Practice: Answer the following exercises about law of cosines.