t=0:0.1:20;
w1=1;w2=4;w3=8;

e1=0.5*cos(w1*t)+1*cos(w2*t+pi/3)+0*cos(w3*t+pi/2);
e2=1*cos(w1*t)+0.5*cos(w2*t+pi/3)+0*cos(w3*t+pi/2);
e3=0.5*cos(w1*t)+1*cos(w2*t+pi/3)+0.5*cos(w3*t+pi/2);
subplot(311)
plot(t,e1);hold on;text(7,1.6,'A1=0.5, A2=1, A3=0');title('A1cos(1*t)+A2*cos(4*t+pi/3)+A3*cos(8*t+pi/2)')
plot(t,0.5*cos(w1*t),'r:');hold on;plot(t,1*cos(w2*t+pi/3),'r:');
subplot(312)
plot(t,1*cos(w1*t),'r:');hold on;plot(t,0.5*cos(w2*t+pi/3),'r:');hold on;
plot(t,e2);text(7,1.6,'A1=1, A2=0.5, A3=0')
subplot(313)
plot(t,e3);hold on;text(7,1.6,'A1=0.5, A2=1, A3=0.5')
plot(t,0.5*cos(w1*t),'r:');hold on;plot(t,1*cos(w2*t+pi/3),'k:');plot(t,0.5*cos(w3*t+pi/2),'m:');hold on;