the ellipse and its evolute
and the distance problem:
updating Apollonius

by Frederick Hartmann and Robert Jantzen [2004, 2008]


For another example of the amazing geometrical ability of Apollonius see:

For a complete study of the evolutes of the graphs of polynomials, see

A similar study of the evolutes of the ellipsoid and its geometry was begun but left unfinished:


A few miscellaneous links: