$\begin{array}{1 1} A_c \sin \{(w_c +K_1 v_m (t))+\phi\} \\ A_c \sin \{(w_ct +\phi +K_2v_m (t))\} \\ \{A_c+K_2v_m(t) \sin (w_ct +\phi)\} \\ A_c v_m (t)\sin (w_ct+\phi) \end{array} $
