i salute the community.


the frequency spectrum of the signal given in the red square here expresses that it is solved in the following way. but everything is so complicated. i mean, I can't figure out why we're doing what we're doing. is there a way to make this more understandable? can you tell me about it?
every help will be honored by the community!
thanks!

 

CERTAINLY the Fourier evaluation is complicated. There is no question about that!! My exposure to the analysis method was in a third semester calculus course many years ago. A good understanding of calculus helps with the details.