Question 1015a

Definite Integrals: Areas and Volumes

Question

(i)
Given that f{f} is a continuous function, explain, with the aid of a sketch, why the value of
limn1n{f(0n)+f(1n)++f(n1n)} \lim_{n \to \infty} \frac{1}{n} \left\{ f \left( \frac{0}{n} \right) + f \left( \frac{1}{n} \right) + \cdots + f \left( \frac{n-1}{n} \right) \right\}
is 01f(x)  dx.{\displaystyle \int_0^1 f(x) \; \mathrm{d}x.}
[2]
(ii)
Hence evaluate
limn1n(sin(0n)+sin(1n)++sin(n1n)).\lim_{n\to\infty} \frac{1}{n} \left( \sin \left( \frac{0}{n} \right)+\sin \left( \frac{1}{n} \right)+\cdots+\sin \left( \frac{n-1}{n} \right) \right).
[3]

Answer