# Thread: Finding Fourier Sine Series Problem

1. ## Finding Fourier Sine Series Problem

$f(x)=\sum_{n=1}^{\infty}b_n\sin\frac{\pi nx}{L}$

f(x) = { 200 for 0<x<pi/2
0 for pi/2<x<pi

Sorry I am not familiar with LaTeX. But I am having trouble with this question. I am also confused about whether the L=pi or L=pi/2?
The answer I get does not seem to agree when I plug in a value for x. So I am at a loss here. Been trying to figure out for hours.

2. ## Re: Finding Fourier Sine Series Problem

Hey mneox.

Hint: Look at the length of the interval over which the function is defined where f(x+L) = f(x).