y[z]=6cos 2 (pi×z/4) a.The above equation shows a discrete time signal, y[z] from a device, determine the four point DFT of the sequence. H(e jw ) = {1, 0≤|w|≤w C {0, W C |W|

y[z]=6cos²(pi×z/4)
a.The above equation shows a discrete time signal, y[z]  from a device, determine the four point DFT of the sequence.


H(e^jw) = {1,     0≤|w|≤w_C

              {0,    W_C
|W|<>

b.The expression above shows the DTFT of a lowpass filter system. In order to get the impulse response h[n], determine the inverse DTFT of the system