Do just that. That is, draw any three circles (of different radii), then use the script on each pair of circles to get the common external tangents.
Can you see any relationships involving the external tangents? Change the positions and radii of your three circles to see if your conjecture holds for a variety of values.
Make sure you make your conjecture before seeing the next page; it is an illustration of the result.
Author: Eduardo Tabacman, revised and edited by Evelyn Sander
Comments to: firstname.lastname@example.org
Created: Jun 09 1996 --- Last modified: Jun 11 1996