Two simple circles

Simon Clay
This worksheet is aimed at deepening understanding of the equation of a circle.
Change one slider so that the circles intersect at two distinct points. Change the sliders so that both circles sit in the first quadrant and each touch the x- and y-axes but not each other. Hide the red circle and set c=d=1 and Radius=2. Adjust one slider so that the circle appears in 3 quadrants. What range of values give solutions?