# Integration Clarification

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• Jun 2nd 2008, 09:18 PM
Evales
Integration Clarification
Haha I just realised that its exam season, have you guys been getting a lot more questions?

Anyway
In some notes that I found on the my schools site there is a rule of sorts to working out what to do when integrating trig.

[sin(x)]^n . dx

It then says that if n is even "change to mulitple angles" What does it mean by multiple angles?

Thanks!
• Jun 2nd 2008, 09:27 PM
Moo
Hello,

Quote:

Originally Posted by Evales
Haha I just realised that its exam season, have you guys been getting a lot more questions?

Anyway
In some notes that I found on the my schools site there is a rule of sorts to working out what to do when integrating trig.

[sin(x)]^n . dx

It then says that if n is even "change to mulitple angles" What does it mean by multiple angles?

Thanks!

Multiple-Angle Formulas -- from Wolfram MathWorld :D

If n is even, you can write : $\displaystyle n=2n'$, $\displaystyle \sin^nx=\left(\sin^2x\right)^{n'}=\left(\frac{1-\cos 2x}{2}\right)^{n'}$

Does it help you ?
• Jun 3rd 2008, 02:52 AM
Evales
I don't know, thanks for that site though it sort of related more to turning multiple angles into ones like (sin x)^n plus other assorted things. More like trig identities.

This kind of makes it hard to reverse and I don't want to make it harder for myself when intergrating.

Any other ideas?