Writing Equations of Hyperbolas and Ellipses from Graphs

Drag points F1 and F2 around. Drag point A around. Drag point B around.
Sometimes the graph is a hyperbola. Sometimes the graph is an ellipse.

What is the equation of the graph?

In the INPUT line below the graph, type in the equation of the graph, using SQRT( ) for the square root.

REMEMBER! You must enter the "top half" and the "bottom half" separately!

Type in sqrt(-9*(1-(x^2/4))) then press enter.
Type in -1*sqrt(-9*(1-(x^2/4))) then press enter.

To reset the graph, click on the small icon in the upper right corner of the graph.

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Steve Phelps, Created with GeoGebra