Determine whether or not each of the following signals is periodic. In case a signal is periodic, specify its fundamental period.

(a) xa(t) = 3 cos(5t + π/6)

(b) x(n) = 3 cos(5n + π/6)

(c) x(n) = 2 exp[j(n/6 - π)]

(d) x(n) = cos(n/8) cos (π n/8)

(e) x(n) = cos(πn/2) – sin(πn/8) + 3cos(πn/4+π/3)