Construct two points O and S and a circle . Keep O fixed and move S so that OS that intersects in two points. Mark the two points of intersection and label them Q and R. Measure OQ and OR and calculate (OQ)/(OR). Now move S (keeping O and fixed) and observe that (OQ)/(OR) remains constant. Verify that this is true whether O is inside or outside .
When I use the move tool to move point S, the product of OQ and OR remains constant.