The applet below depicts the reflective property of an ellipse. The angle in which something reflects off a point is the same as the angle between the initial line/ray and the tangent of that point. In the case of an ellipse, if something is emitted from one foci and reflects off the side of the ellipse, it will always reflect back to the other foci. You can adjust foci A and B to change the dimensions of the ellipse, and you can move point C to see how the reflected lines change as the pint moves.
What is the reflective property of a circle, based off of your knowledge of the reflective property of an ellipse?