
Infinite Sum Limit
I had some trouble with this problem while preparing for the Calculus BC AP test. Any tricks to a solution?
The problem reads:
If $\displaystyle n$ is a positive integer, then $\displaystyle \lim_{n\rightarrow+\infty} \frac{1}{n}\left( \sin \left( \frac{\pi }{n} \right)\; +\; \sin \left( \frac{2\pi }{n} \right)\; +\; ...\; +\; \sin \left( \frac{n\pi }{n} \right) \right)
$
and the answer choices are as follows:
A.) 0
B.) 2/pi
C.) pi/2
D.) 2
E.) 2pi

you know what a Riemann sum is?