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Journal of Convex Analysis 26 (2019), No. 1, 089--104 Copyright Heldermann Verlag 2019 Optimal Constants in Normed Planes Vitor Balestro CEFET/RJ, Campus Nova Friburgo, Nova Friburgo, Brazil vitorbalestro@id.uff.br Horst Martini Fakultät für Mathematik, Technische Universität, 09107 Chemnitz, Germany martini@mathematik.tu-chemnitz.de Ralph Teixeira Instituto de Matemática e Estatística, UFF, Niterói, Brazil ralph@mat.uff.br We define new geometric constants for normed planes, determine their optimal values, and characterize types of planes for which these optimal values are attained. Relations of these constants to several topics, such as areas and distances from points to sides of triangles, are also investigated. We perform some calculations of new and old constants given by trigonometric functions for certain classes of norms, and a conjecture on a certain geometric constant is disproved. Keywords: Banach spaces, geometric constants, Minkowski geometry, Radon norms, sine function. MSC: 46B20; 33B10, 52A10, 52A21 [ Fulltext-pdf (140 KB)] for subscribers only. |