Proof of Fourier Series Coeffecients

podjackel
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Homework Statement



#35 on this page


Homework Equations



Integral of a series can be assumed to be the sum of integrals

The Attempt at a Solution



Picture of Work

I am not sure where to proceed from here, advice?
 
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Try to explicitely calculate

\int_0^\lambda A_n \cos(\frac{2\pi n}{\lambda}x)dx
 
R136a1 said:
Try to explicitely calculate

\int_0^\lambda A_n \cos(\frac{2\pi n}{\lambda}x)dx

This is good advice.
 
Ahh, that whole scary monster is zero! Thanks for the advice. :)
 
Keep an eye on periodicity. It can save you a lot of work.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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