Solving missing lengths and angles of right triangles is a piece of cake if you understand sine, cosine, and tangent. But what can we do if the triangle we’re trying to solve isn’t a right triangle? Fortunately, there is the Law of Cosines. It works for SAS and SSS situations, and there is never an ambiguous case (like there is with the Law of Sines).
Here’s my explanation of this very useful law: