1. The problem statement, all variables and given/known data Prove the law of cosines: If a triangle has sides with lengths a, b, and c, and theta is the angle between the sides a and b, then c^2 = a^2 + b^2 - 2ab*cos(theta). Hint: Introduce a coordinate system so that theta is in standard position. Express x and y in terms of theta and then use the distance formula to compute c. Someone please help me on this. Not sure what is means? Thanks. 2. Relevant equations 3. The attempt at a solution Don't know really where to begin or what is means.