# Proof of Fourier Series Coeffecients

1. Oct 22, 2013

### podjackel

1. The problem statement, all variables and given/known data

2. Relevant equations

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

3. The attempt at a solution

Picture of Work

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

2. Oct 22, 2013

### R136a1

Try to explicitely calculate

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

3. Oct 22, 2013

### brmath

4. Oct 24, 2013

### podjackel

Ahh, that whole scary monster is zero! Thanks for the advice. :)

5. Oct 25, 2013

### brmath

Keep an eye on periodicity. It can save you a lot of work.