Question

Continued product $\cos \alpha \cos 2\alpha \cos 2^2\alpha$ $\cos 2^{n-1}\alpha$

Where, $n\in I$ (Integer)
The value of $\cos \frac{2\pi }{7}\cos \frac{4\pi }{7}\cos \frac{6\pi }{7}$ is -

• A. $-1/2$
• B. $1/2$
• C. $1/4$
• D. $1/8$

Answer 1

Answer: (D)

Correct answer is (d) $1/8$