
Journal for Geometry and Graphics 14 (2010), No. 1, 029043 Copyright Heldermann Verlag 2010 Equioptic Curves of Conic Sections Boris Odehnal Institute of Discrete Mathematics and Geometry, Technical University, Wiedner Hauptstr. 810/104, 1040 Vienna, Austria boris@geometrie.tuwien.ac.at Given two plane curves c_{1} and c_{2} we call the set of points from which c_{1} and c_{2} are seen under equal angle the equioptic curve. We give some basic results concerning equioptic curves in general. Then we pay our attention to the seemingly simple case of equioptic curves of conic sections. Mainly we are interested in upper bounds of the algebraic degree of these curves. Some examples illustrate the results. Keywords: Equioptic curves, isoptic curve, orthoptic curve. MSC: 51N35 [ Fulltextpdf (802 KB)] for subscribers only. 