identities

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- Apr 28th 2008, 03:09 PMcarlasaderidentities
identities

- Apr 28th 2008, 03:14 PMMoo
Hello,

Well, do you know identities for cos(a+b) and cos(a-b) ?

cos(a+b)=cos(a)cos(b)-sin(a)sin(b)

So what will cos(a-b) be ?

For the second one, use twice the formula for cos(a+b) :

cos(3x)=cos(2x+x)=... - Apr 28th 2008, 03:22 PMo_O

Add the equations together.

If A = B:

Convert into terms of only cosA and you should get your answer

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Use your result from the first question to split your products in to sums. It'll be easier to integrate.

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Make the subs:

etc.

You'll need your half-angle identity from your first question to do it after you simplify. - Apr 28th 2008, 03:26 PMMathstud28
- Apr 28th 2008, 03:28 PMMathstud28