[color=#999999]This activity belongs to the [i]GeoGebra book[/i] [url=https://www.geogebra.org/m/sw2cat9w]GeoGebra Principia[/url].[/color][br][br][br]If the point is inside the circle, we obtain an ellipse, and if it's outside, a branch of a hyperbola.[br][br]The implicit curve of the ellipse or branch of the hyperbola is given by the equation:[br]    [br] [color=#CC3300][b]XA – Xc = 0[/b][/color][br]  [br]Note that a construction similar to the one for the parabola also allows us to generate this locus.

[color=#999999]Author of the construction of GeoGebra: [url=https://www.geogebra.org/u/rafael]Rafael Losada[/url].[/color]