Daepp, U., Gorkin, P. and Mortini, R. (2002) Ellipses and Finite Blaschke Products. The American Mathematical Monthly, 109, 785-795.
https://doi.org/10.1080/00029890.2002.11919914

has been cited by the following article:

• TITLE: Enclosing Ellipses by Folding Disks

  AUTHORS: Peter Paul Klein

  KEYWORDS: Straight Line, Perpendicular Bisector, Linear System, Determinant, Point of Intersection, Gardner Ellipse, Bidirectional Folding

  JOURNAL NAME: Applied Mathematics, Vol.13 No.2, February 21, 2022

  ABSTRACT: Ellipses can be constructed by folding disks. These folds are forming an envelope of tangents to the ellipse. In the paper of Gorkin and Shaffer, it was shown that the ellipse constructed by folding can be circumscribed by an arbitrary triangle of tangents, the vertices of which are lying on the circumference of the disk. They offered two non-elementary methods of proof, one using Poncelet’s Theorem, the other employing Blaschke products. In this paper, it is the intention to present an elementary proof by means of analytic geometry.