Hi folks, I know its a long shot, but would anyone like to explain how to integrate the function

f(x) = 2/(pi * r^2) sqrt(R^2 - x^2)

I'm sorry about the poor notation. Please see Wigner semicircle distribution - Wikipedia, the free encyclopedia for a clearer idea.

It's been a long time since I've done integration. I presume it involves a substitution like, say, u = R^2 - x^2. I just can't seem to figure it out.

Got any ideas?