Complex exponential Fourier series coefficients?

[thecastlingking]

Above is a question I need some help with. I can get to a certain point, but I can't get beyond.
Can somebody with knowledge about this help?

 

[jtbell]

It would help us if you show us the work that you've done so far, and tell us the "certain point" at which you get stuck.

Note: we have a way to write equations here:

https://www.physicsforums.com/help/latexhelp/

 

[thecastlingking]

C_n = 3/2 Sa(nπ/2)e^-(jnπ)/2
That is where I get up to, but I don't know what to do from there.
The answer given is: 0 and 3/(jnπ)

 

[LCKurtz]

C_n = 3/2 Sa(nπ/2)e^-(jnπ)/2
That is where I get up to, but I don't know what to do from there.
The answer given is: 0 and 3/(jnπ)

You need to show your work. It looks like you differentiated instead of integrated when calculating the coefficients.