2. Prove the identity:2 cos x cosy = cos(x + y) + cos(x y)Use this identity for the following:a. Define RMS voltage byVins = 4, codeFor time varying voltagev(t) = Vm cos(wt)show that:VRMS = Vm/V2by integrating vt) over a 2-period T of the cosine function.b. Show that:2 cos(wt) cos(ct + (p) = cos p + cos(2wt + (p)