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**delgeezee** I have been getting better but I am having trouble with this evil integral.

Evalute the folling integrel:

$\displaystyle \int_{}{} sin^2(3x+\frac{\pi}{8}) dx$

Here was my first path of deduction

$\displaystyle \int_{}{} sin^2(3x+\frac{\pi}{8}) dx$ ; $\displaystyle u=3x+\frac{\pi}{8}$ ,$\displaystyle u'=3$

dx in terms of u:$\displaystyle 1dx=3du \Rightarrow du=\frac{1}{3}$

$\displaystyle \int_{}{} sin^2(u) \frac{1}{3}du$ = $\displaystyle \frac{1}{3} \int_{}{} sin^2(u)du$ = $\displaystyle \frac{1}{3} \int_{}{} (sinu)^2du$

I am stuck here. I can't directly integrate anything.