The law of sines and the law of cosines both provide a way to solve a triangle given three pieces of information about the sides and angles (other than being given three angles). in what two scenarios must you begin solving the triangle by using the law of cosines?

The Law of Cosine states that
cos
with the lowercase alphabets representing the sides of a triangle and uppercase alphabets representing the angles of the triangle.
This can rearranged to become
cos
Therefore, the two scenarios are either 2 sides and 1 angle of the triangle are provides or 3 sides of the triangle is provided.