Definition of the integral question (Riemann sums?)

The following sum

http://gauss.vaniercollege.qc.ca/web...d534baa891.png

is a right Riemann sum for the definite integral where http://gauss.vaniercollege.qc.ca/web...dd497c3d61.png = ? = 3

and http://gauss.vaniercollege.qc.ca/web...910e13a9c1.png = ? = sqrt(9-x^2)

__The part of the question I'm stuck on is:__

The limit of these Riemann sums as http://gauss.vaniercollege.qc.ca/web...63147a7bc1.png is = ?

I know that I need to evaluate:

lim(n->inf) sum from 0 to n of sqrt(9-(3i/n)^2) but after scaring the 3i/n part, I'm stuck.

Any help would be GREATLY appreciated!

Thanks in advance!

P.S.

Does this whole question involve a topic called "Riemann sums?"