# How to calculate this trig integral?

• April 25th 2009, 06:32 AM
curvature
How to calculate this trig integral?
Can anybody help with this integral:
$\int {xcos^{2009}xdx}$?
Thanks.
• April 25th 2009, 07:15 AM
Nacho
an idea

first integrate byr part, to eliminate that X, next you can usea the indetity

$
\cos ^2 x = \frac{{1 + \cos \left( {2x} \right)}}
{2}
$

next you have to find a regularity... (wich I didn`t find it)
• April 25th 2009, 07:19 AM
derfleurer
Unless you've got some technique for integrating that, this looks like burnt toast, mate. =p