Hi,

I was recently doing some revision and encountered a slight problem with my an calculation for the fourier series..

heres the problem

f(x)=0 -pi<x<-pi/2

f(x)=4 -pi/2<x<pi/2

f(x)=0 pi/2<x<pi

f(x)=f(x+2*pi)

consider one cycle between x=-pi and x=pi

when i calculated the an, I got 8/(pi*n) but in the textbook it says8/(pi*n)sin(n*pi)/2 so could someone explain how thesin(n*pi)/2 came about?? Your help would be much appreciated..(Rock)