I'm stumped on these problems:

Find the anti-derivative

a) f ''(t) = 2e^t+2 sint, f(0)=0 f(pi)=0

b)f'(x) = 3/(sqrt(1-x^2)), f(1/2)=6

If someone could explain how to do it? I got stuck on the first one toward the end of the problem. I'm stumped on b). Thanks for any help!