Have completely forgotten how to prove that a sinusoidal waveform is periodic and can't seem to find it anywhere. So was hoping someone could here.
I've got the signal x(t)=cos(2t+pi/4)
and am trying to prove it is periodic.
The Attempt at a Solution
I know that it is periodic, but to prove I think I have to prove that x(t)=0
Have tried letting t=-pi/8 but with the phase change of pi/2 to convert it to a sine again it gives me a non zero answer.
Anyone with any help would be greatly appreciated.