The following sum
[(sqrt(36-((6/n)^2))).(6/n)] +
[(sqrt(36-((12/n)^2))).(6/n)]+ ... + [(sqrt(36-((6n/n)^2))).(6/n)]
is a right Riemann sum for the definite integral F(x) dx from x=0 to 6
Find F(x) and the limit of these Riemann sums as n tends to infinity.