The following sum

is a right Riemann sum for the definite integral where = ? = 3

and = ? = sqrt(9-x^2)

The part of the question I'm stuck on is:

The limit of these Riemann sums as 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?"