Periodic versus non-periodic functions (hw1, ECE301)

Read the instructor's comments here.

Periodic Function

Periodic function of CT is y(t)=sin(t).

Proof: y(t+T)= sin(t+T),where we take T=2*pi.
       so sin(t+T)=sin(t+2*pi)=sin(t)
       i.e y(t+T)=y(t).
       so it's periodic function.

Non-Periodic Function

Non-periodic function is $ y(t)=t $.

Proof: assume y(t) is periodic, then there exists a non-zero T,that makes y(t+T)=y(t) 
       i.e. t+T=t,so T=0,which violates the assumption.
       So y(t)=t is a non-periodic function