Possible Duplicate:
Riemann’s Integrals Question
I have the following question, $ \lim_{n\to\infty} \sum_{i=1}^n \tan((\frac \pi {3n})i) \times \frac \pi {3n} $
and was wondering which limit laws I could use to work out the answer? this question is derived from a riemann integral question. I know I can take out the $\frac \pi {3n} $ outside the summation so I'm left with
$ \lim_{n\to\infty} \frac \pi {3n} \sum_{i=1}^n \tan((\frac \pi {3n})i) $
but I'm not sure what to do next?