A parabola can be defined symbolically by parameters [i]a[/i] and [b][i]b[/i][/b] or by location of a focus and a directerix. What are the relations between these representations? [br][br]In the left panel you can define a blue parabola by varying the values of the [b][i]a[/i][/b] and [b][i]b[/i][/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.[br][br]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.