Signal
We will compute the Power and Energy of a 440HZ sin wave, also known as an "A".
$ x(t)=sin(2\pi440t)\! $.
Average Power
Average power of the 440 Hz sine wave.
$ E=\frac{1}{2\pi-0}\int_0^{2\pi}{|sin(2\pi440t)|^2dt} $
$ =\frac{1}{2\pi-0}\frac{1}{2}\int_0^{2\pi}(|1-cos(4\pi440t)|)dt $
$ =\frac{1}{4\pi}(t+\frac{1}{4\pi440}sin(4\pi440t))|_{t=0}^{t=2\pi} $
$ =\frac{1}{4\pi}(2\pi+(1.7305e^-4)-0-0) $
$ =\frac{1}{2} $