Concentric Circles

The circles below are concentric. Each slider controls the circle with the matching color. Adjust the sliders to alter the size of the circles. [br]1. Which color slider allows the largest radius? Which one allows the smallest radius?[br]2. What do you have to do to get the concentric circles congruent (to lay on top of one another)?[br]3. Can you set up two sets of congruent circles?

Information: Concentric Circles