Hello I could use some help understanding this problem. We are to prove that the orthogonality relation of this problem. Assuming m and n are integers with m not equal to n. With a definite integral of 0 to pi (Sorry i don't know how to type the problem out properly on here)
∫sin(mx)sin(nx)dx = 0
Any advice would be appreciated! Thanks!
hint: Use this identity: $$sin(a)sin(b)={1\over2}[cos(a-b)-cos(a+b)]$$