Throughout the chapter we focused on c(t) = a_c cos(2 pi f_c t) as the sinusoidal carrier wave. suppose we choose c(t) = a_c sin(2 pi f_c t) as the sinusoidal carrier wave. to be consistent, suppose we also define m(t) = a_c sin(2 pi f_m t) evaluate the spectrum of the new definition of am: s(t) = a_c[1 + k_a m(t)] sin (2 pi f_c t) where k_a is the amplitude sensitivity. compare the result derived in part (a) with that studied in example 3.1. what difference does the formulation in this problem make to the formulation of modulation theory illustrated in example 3.1? consider the message signal m(t) = 20 cos(2 pi t) volts and the carrier wave c(t) = 50 cos(100 pi t) volts sketch (to scale) the resulting am wave for 75 percent modulation. find the power developed across a load of 100 ohms due to this am wave.