What I dont understand is how he got from 2 to 3 and from 4 to 5. For three, I had this:

Where c is a place holder for cos 2x.

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- December 10th 2012, 05:57 AMNervousI dont know how he got this...

What I dont understand is how he got from 2 to 3 and from 4 to 5. For three, I had this:

Where c is a place holder for cos 2x. - December 10th 2012, 09:40 AMhairymclairyRe: I dont know how he got this...
Check your calculation from step 2 to step 3, since by my reckoning

For the final step Wikipedia is certainly your friend:

List of trigonometric identities - Wikipedia, the free encyclopedia

You can use the half angle, double angle and triple angle identities to make the last two integrations in step 4 manageable. - December 10th 2012, 03:13 PMNervousRe: I dont know how he got this...
Wow, I wrote down the problem wrong, I had sine and cosine switched. I copied the above straight from the book, so it's correct. I wrote it wrong in my note book. I swear, I need to postpone calculus until I get down basic reading and writing...