Apollonian Gasket

3 points determine the outside circle used for packing circles in the form of an Apollonian gasket. A Euclidean construction (compass & straightedge) is shown in the file (gasket.ggb) at the bottom of the page. The open-source software is available from www.geogebra.org

The following constructions are from the file.

The 3 points of the starting circle can be moved so that the circle is an inside circle: