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

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.