Question

Find the fundamental period of 1+sin^2 (3π/5)n.

(a) 10/3

(b) 5

(c) 3π/5

(d) None of the mentioned

I had been asked this question by my school principal while I was bunking the class.

The doubt is from Classification of Signals topic in chapter Signals and Spectra of Digital Communications

Answer 1

Correct option is (b) 5

The best I can explain: sin^2(3π/5)n = (1-cos(6π/5)n)/2 = 1/2-1/2cos(6π/5)n ; period = 6π/(5*2π) = k/N = 3/5 ; N=5.