1. It is important to be aware of the fact that the identities cos(2Tjt)=cos(2TTjt)sin(2Tjt)=sin(2TTjt)fort=1,2,,T are in fact a case of aliasing; to appreciate this, figure out (b) what are the periods and frequencies of functions cos(2TTjx) and sin(2TTjx); (c) and finally show the identities above hold true for t=1,2,,T..