# Integration of circle?

1. Jul 28, 2012

### gtfitzpatrick

1. The problem statement, all variables and given/known data
-8$\int^{3}_{0}\sqrt{9-x^2}dx$

2. Relevant equations

3. The attempt at a solution

am i right in thinking this the area of a circle in the first quadrant so my answer is-8($\frac{9\pi}{4})$ = -18$\pi$

2. Jul 28, 2012

### Dick

Sure it is.

3. Jul 28, 2012

### gtfitzpatrick

Hi Dick.
are you saying "it sure is" or are you asking "are you sure it is?"

"sure it is" is the way my friends would sarcastically say "your wrong"

4. Jul 28, 2012

### Dick

It's the not sarcastic 'it sure is'. The integral is -18*pi and you can deduce that from its being a quarter circle. You could also do it with a trig substitution and get the same thing.

5. Jul 28, 2012

### gtfitzpatrick

thanks a million Dick.