Problems with some integration

Hi, im new here, I have some problems with the following integrations:

I've tried various things with all of them, but cant figure them out. I'd love some pointers, hopefully with explanations :)

1. $\displaystyle \int \frac {\sin^3(x)} {\cos^2(x)}dx $

2. $\displaystyle \int^{\frac{\pi}{2}}_{0} \frac {\sin(3x)} {\cos(3x)} dx $ with a suitable substitution is? Apparently the answer is: $\displaystyle \int^{1}_{0} \frac {1}{3u} du $, but im not sure what i should pull put as 'u'. Any ideas?

3. The area of the region bounded by the axis, the line x=1 and the curve: $\displaystyle y = \frac {1}{\sqrt{4-3x^2}}$, so i presume we need to get the definite integral from 0-1 of that curve, but once again i cant figure out the answer.

I'll add to this list as more problems arise.

Thanks for the help :)