Q. $cos (\frac{π}{11}) + cos (\frac{3 π}{11}) + cos (\frac{5 π}{11}) + cos (\frac{7 π}{11}) + cos (\frac{9 π}{11}) =$

1682 244 Odisha JEEOdisha JEE 2010Trigonometric Functions Report Error

A

$1/3$

B

$1/2$

C

$1$

D

$- 1$

Solution:

Correct answer is (b) $1/2$