It's been a while since I've worked these types of problems, but I've been working out the following problem for a while now and can't figure out a few details:
Most of the solution makes sense, but I just have a few things I'm not able to clarify, namely:
How were they able to determine the h(t) is a low pass filter? And which fourier coefficients will be passed through? Seems like n=2=-2 should be a valid coefficients too
How did they get h(t) into the frequency domain?
Any help is appreciated