Hi, can anyone help me solve this:

2 functions f and g are orthogonal on [a,b] if:

$\displaystyle \int_a^b f(x)g(x)dx = 0$

Prove that $\displaystyle f_{m}(x) = $sin$\displaystyle mx$ and $\displaystyle f_{n}(x) = $sin$\displaystyle nx$ are orthogonal on the interval $\displaystyle [-\pi,\pi]$ if m and n are integers such that $\displaystyle m^2$ ≠ $\displaystyle n^2$

Thanks.