I have to integrate by substitution:

$\displaystyle \int csc^2(3x+5)\frac{\pi}{4}dx

$ between 8/3 and 2

tried making (3x+5)=u to give:

$\displaystyle \int csc^2\frac{\pi u}{4}\frac{du}{3}

$

I'm not sure if this is correct though, and I don't know how to integrate trig functions when the variable has a coefficient. Please help.