# trigonometric integrals

• November 8th 2009, 07:30 PM
abilitiesz
trigonometric integrals
Hi, I need some help on this trig integral problem.

Can anyone tell me how to start this? I know I need to use some kind of identity to change the sec to cos or sin? Thank you.

http://img149.imageshack.us/img149/6751/mathxg.th.jpg
• November 8th 2009, 08:57 PM
WhoCares357
Quote:

Originally Posted by abilitiesz
Hi, I need some help on this trig integral problem.

Can anyone tell me how to start this? I know I need to use some kind of identity to change the sec to cos or sin? Thank you.

http://img149.imageshack.us/img149/6751/mathxg.th.jpg

$\int 54x^4sec^4(x^5)dx$
$54\int x^4(sec^2(x^5))(sec^2(x^5))dx$
$54\int x^4(sec^2(x^5))(1+tan^2(x^5))dx$

Can you take it from here?
• November 8th 2009, 09:32 PM
abilitiesz
Yes, I can take it from there. Thank you. :) I figured it out.