Answer:
x = 2* pi* n
Step-by-step explanation:
cos(2x) cos(x) + sin(2x) sin x =1
We know cos(s) cos(t) + sin(s) sin(t) = cos(s - t)
Using s =2x and t = x
cos (2x-x) =1
cos (x) =1
We know this occurs at 0, 2pi, 4 pi etc
x = 2* pi* n where n is an integer
