Integral of cos(^3)2x i did - cos2x X cos(^2)2x Then changed cos(^2)2x to 1-sin(^2)2x How do i proceed now?
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The derivative of $\displaystyle \sin^2(2x)$ is $\displaystyle 4\sin(2x)\cos(2x)$.
Yes ok, i substituted that.what do i do next?
I would probably do a $\displaystyle u$ substitution from your $\displaystyle \cos(2x)(1-\sin^{2}(2x)):$ $\displaystyle u=\sin(2x).$
Yes,the substitution worked.Thanks But is there also any other way to do it?
Yes. $\displaystyle \cos3{\theta} = 4\cos^3{\theta} - 3\cos{\theta}$ From the above equation find cos^3(x) and then find the integration.
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