Question

If S = cos² π/n + cos² 2π/n + ....+ cos²(n - 1)π/n,  then S equals

(A)  n/2(n + 1)

(B)  1/2(n - 1)

(C)  1/2(n - 2)

(D)  n/2

Answer 1

Correct option (C) 1/2 (n-2)