# integration problem..plz help, I'm clueless...

• Nov 9th 2008, 03:48 AM
KAS
integration problem..plz help, I'm clueless...
This question is really confusing..I'm frustrated with it..
evaluate:

∫cos^(n)x

I tried solving it..
by these two steps:

∫cos^(n-1) x. cosx dx

∫cos^(n-1) x d(sinx)
I then stopped..I felt it's becomming more complicated..can ne1 help by giving me an easier way?
• Nov 9th 2008, 04:52 AM
Krizalid
No! Actually, you're doing well!

See my signature, that'll feed you up. (Integration by parts.)
• Nov 9th 2008, 08:00 AM
Mathstud28
Quote:

Originally Posted by KAS
This question is really confusing..I'm frustrated with it..
evaluate:

∫cos^(n)x

I tried solving it..
by these two steps:

∫cos^(n-1) x. cosx dx

∫cos^(n-1) x d(sinx)
I then stopped..I felt it's becomming more complicated..can ne1 help by giving me an easier way?

Note that this will never give you a definite answer, but what is known as a reduction formula. Look it up on Wikipedia.
• Nov 10th 2008, 09:18 AM
KAS
Krizallid..thanx.. ur method seems to be very effective..ill try use it ..
mathstud yeh.. it doesn't seem to be the type of question where a definite answer will be found..ill try look at what u sed on wiki.it might be useful..

thanx again ...