# Integral of expression with radical

1. Feb 2, 2012

### ghastlymeanlo

1. The problem statement, all variables and given/known data
There's a problem that involves triple integrals, but basically, I've boiled all of it down to the following single integral but cannot proceed any further.

∫u2 sqrt(a2-u2) du
from 0 to a

where a is a constant

2. Relevant equations

3. The attempt at a solution

I attempted to use a change of variables, where
v = a2 - u2 and
dv = -2udu

but i still can't integrate it after substituting in for all u's.

2. Feb 2, 2012

### vela

Staff Emeritus
How about a trig substitution?