beginfig(4)
xcenter=2;
ycenter=6;
radius=1.5;
z1=(xcenter+radius,ycenter);
z2=(xcenter,ycenter-radius);
z3=(xcenter-radius,ycenter);
z4=(xcenter,ycenter+radius);
draw z1..z2..z3..z4..cycle;
endfig;
end