Determine for each of following 4 signals if it is bandlimited and, if yes, find the minimum
sampling rate without causing aliasing.
(a) x1(t) = cos(500pt) + sin(700pt); (b) x2(t) = sin2(50pt);
(c) x3(t) = sin(50pt)rect(100t), where rect(t) =1, |t| < 1/2; 0, otherwise
(d) x4(t) = g2(t), where g(t) is bandlimited with highest frequency 100p rad/sec.