You wrote: > Date: Wed, 21 Jun 2006 19:43:46 -0400 > From: Sam Kutler <firstname.lastname@example.org> > Subject: [HM] An Arbitrary Quadrilateral > > I just came across this geometrical theorem: > > Consider the centers of squares drawn outward he on the sides of > an arbitrary quadrilateral. > Join the opposite centers with line segments. > > Then, the line segments are equal and cut each other orthogonally. > > This seems to me a beautiful result. Have you seen it, > and if so, how far back can you trace it?
In Dutch literature the theorem is know as: Van Aubel's theorem (Henri van Aubel, 1830-1906).