Energy of 2cos(t)
E = $ \int_{0}^{2\pi} \vert 2cos(t) \vert^2 \ , dx $
= $ 4/2 \int_{0}^{2\pi} (1 + 2cos(t)) \ , dx $
= 2(t + sin(2t))
= $ 2\pi $
Power of 2cos(t)
P = $ 1/2\pi \int_{0}^{2\pi} \vert 2cos(t) \vert^2 \ , dx $
= $ 4/4\pi \int_{0}^{2\pi} (1 + 2cos(t)) \ , dx $
= $ 1/\pi(2\pi + 0) $
= 2
