x=[-3.5:0.01:3.5];
n=size(x,2);
y1=zeros(n,1);
y2=zeros(n,1);
for i=1:n
  y1(i)=cos(x(i)/2)^2;
  y2(i)=sin(x(i)/2)^2;
end;
plot(x,y1,'black');
hold on;
plot(x,y2,'LineWidth',1.5,'Color','black');
axis([-3.5 3.5 -0.5 1.5]);
hold off;
axis on;
