Vc = 1;

wc = 2*pi*100;
wm = 2*pi*5;

t = 0:0.0001:1;

var = 1;
for Vm = [0.5 1 2]
    Vam = Vc.*cos(wc.*t).*(1 + Vm.*cos(wm.*t));
    subplot(3,1,var)
    plot(t, Vam)
    hold on
    plot(t, Vm.*cos(wm.*t)+Vc, 'r')
    plot(t, -(Vm.*cos(wm.*t)+Vc), 'r')
    
    var = var + 1;
   
end