I've tried simplifying the equation first but got stucked instead, and tried substitution also.

Which method should i use for this?

Thanks in advance.

Printable View

- December 14th 2012, 03:56 AMtempq1Integration Help on trigo

I've tried simplifying the equation first but got stucked instead, and tried substitution also.

Which method should i use for this?

Thanks in advance. - December 14th 2012, 04:21 AMkspkidoRe: Integration Help on trigo
hmmm why don't you try to first factor sin^3(2x) to sin^2(2x)(sin(2x))... then since sin^2(2x) is also equal to 1-cos^2(2x).... you rearrange it to a indefinite integral of cos^4(2x)[1-cos^2(2x)]sin(2x)dx.. :) then do substitution... u=cos (2x).... :) du= (2)(-sin(2x))dx.... now... please do the rest :)

- December 14th 2012, 04:23 AMMarkFLRe: Integration Help on trigo
Try rewriting the integrand as follows:

Can you proceed from here using an appropriate substitution? - December 14th 2012, 08:50 AMhollywoodRe: Integration Help on trigo
At my university, students are taught general methods for the integrals and . The substitution depends on whether n and m are even or odd - it's actually pretty straightforward if you look at the derivatives of those four trigonometric functions.

- Hollywood - December 14th 2012, 06:29 PMtempq1Re: Integration Help on trigo
Thanks guys question solved. Just another question

i tried changing it into

and got stuck.

ps:can't seem to edit my original post. - December 14th 2012, 10:36 PMMarkFLRe: Integration Help on trigo
I would use a Pythagorean identity to rewrite the integrand as:

and then use the fact that:

to rewrite the integral as: