Build & Fit - Parabola
A parabola can be defined symbolically by parameters a and b or by location of a focus and a directerix. What are the relations between these representations?
In the left panel you can define a blue parabola by varying the values of the a and b sliders. In the right panel you define the green parabola by adjusting the location of the focus and the directerix. Now try to vary the green parabola to match the blue one.
Alternatively, start by defining a green parabola in right panel, and see if you can adjust the a and b parameters in the left panel so that the blue parabola matches the green one.