# Math Help - Law of Cosines

1. ## Law of Cosines

Use the Law of Cosines to prove the identity

(cosA/a) + (cosB/b) + (cosY/c) =
(a^2 + b^2 + c^2)/(2abc

2. Originally Posted by magentarita
Use the Law of Cosines
yes ! That's exactly what you have to do !