MATLAB: How to get in a plot a circle and not an ellipse

Question

Hi all, How to get in the figure a circle and not an ellipse. Thank you

t=0:2*pi/50:2*pi;
y=1*sin(4*t);
figure(1);hold on; polar(t,5+y,'-r');ezpolar('5');hold off;

Answer 1

Specify axis square:

t=0:2*pi/50:2*pi;
y=1*sin(4*t);
figure(1);hold on; polar(t,5+y,'-r');ezpolar('5');hold off;axis square