for this partice could u help me

Consider the process defined as follows: It = Cos 2 7 ( 12+ for t = 0, +1, 12, ... where o is selected from a uniform distribution on the interval from 0 to 1. (a) Show that Er ] = 0 for all t. (b) Show that Cov(It, Is) = = cos |2x It - s 12 Is {r } stationary? (c) Suppose that the process defined as follows: It = Rcos 27 ( 12 to ) ] for t = 0, +1, 12, ... where R and o are uncorrelated random variables, and o is selected from a uniform distribution on the interval from 0 to 1. Show that Cov(It, Is) = E(R2) 2cos |2x It - s/ 12