We got this question to solve:
Calculate the power of the signal: $$s(t) = 8\cos\left(20\pi t-\frac \pi4\right) + 4\sin(15\pi t)$$
Now, I thought of two approaches :
Use Parseval theorem, so first find Fourier transform, then calculate the required integral, but then we get a impulse function in it and I don't know how to integrate square of $\delta$.
Using the normal formula to calculate the power of a signal, and again in that, we get 3 terms, $\sin^2$ which is easy, then $\cos^2$ again simple, and then $\sin\cdot \cos$, which I know how to solve, but will be lengthy and I think there should be some another proper way to solve this question.
Any guidance would be appreciated.