Question

A telescoping series is a series whose general term $t_n$ can be written as $t_n=a_n-a_{n-1}$ i.e the difference of two consecutive terms of a sequence $\left(a_n\right)$.
The value of $\frac{\sec x}{2}+\frac{\sec x\sec 2x}{2^2}+\frac{\sec x\sec 2x\sec 2^{2}x}{2^3}+\dots \dots 8$ terms $=\cos \theta \left(0<\theta <\frac{\pi }{2}\right)$ when $x=\frac{\pi }{512}$ then $\cos (1024\theta )=$

Answer 1

Answer: 1

Correct answer is (a)