Why is $\sum_{n=0}^{N}{\cos nx}={1\over 2}+{1\over 2}\sum_{-N}^{N}e^{inx}$? I have gone through all the identities relating Fourier series and I can't seem to understand why. In this question, the assumption is that the functions are $2\pi$ periodic(In some places the initial assumption is that the functions are, for example 1- periodic and then the $2\pi$ is being placed within the function instead. I am sorry if you didn't understand what I meant. I am not native and find some things hard to express.). I could really use your help.
2026-05-16 21:50:01.1778968201
Why is $\sum_{n=0}^{N}{\cos nx}={1\over 2}+{1\over 2}\sum_{-N}^{N}e^{inx}$?
58 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail AtRelated Questions in CALCULUS
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