I'm not asking the solution, but rather the main idea of how to solve the part 2:
1)Find the Fourier development of with .
2)Show using the previous result that .
Attempt: Is it just by using Parseval's theorem?
I'm not asking the solution, but rather the main idea of how to solve the part 2:
1)Find the Fourier development of with .
2)Show using the previous result that .
Attempt: Is it just by using Parseval's theorem?