Question

Let f (x) denote the sum of the infinite trigonometric series, 

Find f (x) (independent of n) also evaluate the sum of the solutions of the equation f (x) = 0 lying in the interval (0, 629).

Answer 1

now substituting n = 1, 2, 3, 4.......

= 1/2 [1 – cos x] now f (x) = 0

⇒ cos x = 1 x = 2nπn∈I