For the deteministic signal y(t)-2+3sin(6πt)+4sin(18πt), sketch the amplitude-frequency spectrum of y(t) a when the sinal is sampled at a rate of 24 hz( indicate by solid lines) and b when it is sampled at a rate of 2 hz indicate by dashed lines. finally c determine the minimum sample period in s to avoid amplitude ambiguity in the amplitude-frequency spectrum.