
Journal for Geometry and Graphics 24 (2020), No. 2, 159173 Copyright Heldermann Verlag 2020 The Ellipse, Monge’s Circle and Other Circles Maurizio Ternullo INAF  Osservatorio Astrofisico di Catania, Catania, Italy mternullo@oact.inaf.it [Abstractpdf] New developments of the author's research project on the geometry of conics are presented. For any general point $P$ taken on a given ellipse $H$, some triplets of collinear, peculiar points are described; several angles sharing the same vertex are shown to share the same line as bisector, too. Three new circles linking points belonging to the ellipse $H$, Monge's circle and other conics introduced by the author (the symbiotic ellipse $H_{\Sigma}$ and the circle $\Phi_1$) are described. Unsuspected relationships linking the newly defined objects with a circle previously introduced by the author (denoted \emph{circle $\Omega$}) are described. Keywords: Ellipse, collinear points, angle bisector, concyclic points, symbiotic conics, Monge's circle, bridgecircle. MSC: 51M04 [ Fulltextpdf (2931 KB)] 