The signal is: x(t) = 2cos(2t)
Energy
$ \int_0^{2\pi}{|2cos(2t)|^2dt} $
$ = 4 \times \frac{1}{2}\int_0^{2\pi}(1+cos(4t))dt $
$ =2 \times (t+\frac{1}{4}sin(4t))|_{t=0}^{t=2\pi} $
$ =2 \times (2\pi+\frac{1}{4}-0-0) $
$ =4*\pi + \frac{1}{2} $
Average Power
$ \frac{1}{2\pi-0}\int_0^{2\pi}{|cos(t)|^2dt} $
$ =\frac{1}{2\pi-0}\frac{1}{2}\int_0^{2\pi}(1+cos(2t))dt $
$ =\frac{1}{4\pi}(t+\frac{1}{2}sin(2t))|_{t=0}^{t=2\pi} $
$ =\frac{1}{4\pi}(2\pi+0-0-0) $
$ =\frac{1}{2} $
