import geometry;
size(8cm,0);
currentcoordsys=cartesiansystem((2,1),i=(1,0.5),j=(-0.25,.75));
show(currentcoordsys);
point A=(1,1);
dot("$A$",A,S,red);
real R=2;
circle C=circle(A,R);
draw(C,Arrow);
/**/
ellipse el=xscale(2)*C;
draw(el,blue,Arrow);
// /**/
ellipse el=xscale(2,A)*C;
draw(el,red,Arrow);