Trig Integration

• October 9th 2007, 05:11 PM
ff4930
Trig Integration
Integral of cos^6x dx

Ive tried breaking it apart different powers but I can't figure out the correct combination.
• October 9th 2007, 05:16 PM
Jhevon
Quote:

Originally Posted by ff4930
Integral of cos^6x dx

Ive tried breaking it apart different powers but I can't figure out the correct combination.

try integration by parts
• October 9th 2007, 05:18 PM
ff4930
This problem said to solve it using trig.

breaking it into

cos^4x and cos^2x dont seem to help
=(1-sin^2x)^2 cos^2x
• October 9th 2007, 05:49 PM
qbkr21
Re:
Re:
• October 9th 2007, 05:55 PM
ff4930
Problem is cos^6x not sin^6x
• October 9th 2007, 06:16 PM
Krizalid
Quote:

Originally Posted by ff4930
Integral of cos^6x dx

As Jhevon already told ya, integrate by parts.

--

But, it doesn't make much sense to integrate $\cos^6x,$ so I'd prefer to compute

$\int\cos^nx\,dx$

which contains a lot of sense, I mean, a reduction formula.