The frequency which, under the sampling theorem, must be exceeded by the sampling frequency is called the Nyquist rate. Determine the Nyquist rate corresponding to each of the following signals:
a) x(t) = 1 + cos(2,000πt) + sin(4,000πt)
b) x(t)= sin(4000 π t) / π t
c) x(t)= 2 [sin(4000 π t) / πt]2
