a-n-k-1-n-1-sin-2k-1-pi-2n-cos-2-k-1-pi-2n-cos-2-kpi-2n-find-lim-n-a-n-n-3-

Question Number 98557 by M±th+et+s last updated on 14/Jun/20

a_{n} = \underset{k = 1}{\sum^{n - 1}} \frac{s i n (\frac{(2 k - 1) π}{2 n})}{{c o s}^{2} (\frac{(k - 1) π}{2 n}) {c o s}^{2} (\frac{k π}{2 n})}

f i n d \underset{n \to \infty}{l i m} \frac{a_{n}}{n^{3}}