Fourier Series Representation Problem

[metgt4]

Homework Statement

Since I don't know how to insert equations into a message here, I've scanned both the problem and my attempt at a solution. Where I run into problems is how to find a_n. I'm not completely sure how to treat that integral and was hoping somebody could nudge me in the proper direction.

Thanks!
Andrew

 

[vela]

You messed up writing down the second integral when you integrated by parts, specifically, you dropped the n in the argument. Otherwise, you look like you're on the right track.

 

[metgt4]

Thanks! I wrote that in a bit of a rush but so long as the idea is right I'll keep working with it.