Homework 1: (Sampling) Consider three analog signals sampled at the same rate of 8000Hz given by: x(t)=6cos(4000t)+3cos(6000t) for t0 1. Sketch the spectrum of these three original signals. 2. Sketch the spectrum of sampled signals up to 20KHz. 3. Sketch the recovered analog signals spectrum if an ideal low pass filter with cut-off frequency of 4kHz is used to filter the above sampled signals in order to recover the original signals