I chose Kathleen Schremser's CT signal y(t)=sin(3/4*t).
In the given signal:
frequency=w=3/4
In order for a CT signal to be periodic in DT the frequency divided by 2*pi must be a rational number.
k is any integer
therefore:
$ w/(2*pi)=k/N (3/4)/(2*pi)=0.119366207318922 $
Since this is not a rational number the signal is not periodic in DT.
If we change the signal to y(t) = sin(2*pi*(3/4)*t) then;
frequency=w=3/4 * 2*pi
$ w/(2*pi)=3/4 $
Since this is a rational number the signal is periodic in DT
