Use substitution rather than parts.
I've been trying to integrate this by parts, and I'm failing miserably because no matter how I do it, I just make the integral more complicated or get something that doesn't make any sense at all, so it's pretty useless to put up any attempts at this problem.
Alright, I'm pretty rusty on the details of substitution since we learned that several months ago lol but I've got this so far
(tan u)^2 du
and now im stuck again. If I split tan^2 u into sin^2 u/cos^2 u, then I can't figure out what to substitute next. Sorry I need so much help on this problem, I'm pretty embarrassed considering that (tan u)^2 isn't that elaborate of a function :/
Thanks so much you guys!