Build & Fit - hyperbola

An hyperbola can be defined symbolically by parameters a and b or by location of two foci and a point on the hyperbola. What are the relations between these representations? In the left panel you can define a blue hyperbola by varying the values of the a and b sliders. In the right panel you define the green hyperbola by adjusting the location of the foci and a point (the BLACK dot) on the green hyperbola. Now try to vary the green hyperbola to match the blue one. Alternatively, start by defining a green hyperbola in right panel, and see if you can adjust the a and b parameters in the left panel so that the blue hyperbola matches the green one. What questions could/would you pose to your students based on this applet ?