Solving Fourier Series Prob: Need Help With Integral Parts

[math&science]

I've got parts of this problem but I'm stuck on some of the integration. See attached. Thanks!

 

[HallsofIvy]

First, since an interval is 0 to $\pi$ what are you integrating over 0 to [itex]\pi/2[/tex]?<br /> <br /> Second, since cos x is positive from 0 to $\pi/2$ and negative from $\pi/2$ to $\pi$, you can replace |cos(x)| with <br /> cos(x) from 0 to $\pi/2$ and with -cos(x) for $\pi/2$ to $\pi$.[/itex]

 

[math&science]

First, since an interval is 0 to $\pi$ what are you integrating over 0 to [itex]\pi/2[/tex]?<br /> Second, since cos x is positive from 0 to $\pi/2$ and negative from $\pi/2$ to $\pi$, you can replace |cos(x)| with <br /> cos(x) from 0 to $\pi/2$ and with -cos(x) for $\pi/2$ to $\pi$.[/itex]

$<br /> I changed the interval I was integrating over b/c that's part of the equation. You can't integrate from -l to l so you change it to 0 to l where l is half of the fundamental period and instead of multiplying the integral by 1/l, I changed it to 2/l. Is it easier to just integrate from -l to l?$