Find ∫02πeinθe−imθdθ\int_0^{2\pi} e^{in\theta} e^{-im\theta} d\theta∫02πeinθe−imθdθ.
2π2\pi2π if n=mn=mn=m, 000 otherwise
000 always
2π2\pi2π always
111 if n=mn=mn=m, 000 otherwise