I have a DEplot :

DEplot(sys, [x(t), y(t)], t = 0 .. 30, [[x(0) = 0.8, y(0) = 0]], x = -1.25 .. 1.25, y = -1.25 .. 1.25, numpoints = 300, axes = boxed);

I would like to draw on this plot two circles centered in the origin with different radiuses.

How can I proceed?