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Main Authors: Dipierro, Serena, Noakes, Lyle, Valdinoci, Enrico
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2403.02830
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author Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
author_facet Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
contents As is well-known, numerical experiments show that Napoleon's Theorem for planar triangles does not extend to a similar statement for triangles on the unit sphere $S^2$. Spherical triangles for which an extension of Napoleon's Theorem holds are called ``Napoleonic'', and until now the only known examples have been equilateral. In this paper we determine all Napoleonic spherical triangles, including a class corresponding to points on a 2-dimensional ellipsoid, whose Napoleonisations are all congruent. Other new classes of examples are also found, according to different versions of Napoleon's Theorem for the sphere. The classification follows from successive simplifications of a complicated original algebraic condition, exploiting geometric symmetries and algebraic factorisations.
format Preprint
id arxiv_https___arxiv_org_abs_2403_02830
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Napoleonic triangles on the sphere
Dipierro, Serena
Noakes, Lyle
Valdinoci, Enrico
Analysis of PDEs
As is well-known, numerical experiments show that Napoleon's Theorem for planar triangles does not extend to a similar statement for triangles on the unit sphere $S^2$. Spherical triangles for which an extension of Napoleon's Theorem holds are called ``Napoleonic'', and until now the only known examples have been equilateral. In this paper we determine all Napoleonic spherical triangles, including a class corresponding to points on a 2-dimensional ellipsoid, whose Napoleonisations are all congruent. Other new classes of examples are also found, according to different versions of Napoleon's Theorem for the sphere. The classification follows from successive simplifications of a complicated original algebraic condition, exploiting geometric symmetries and algebraic factorisations.
title Napoleonic triangles on the sphere
topic Analysis of PDEs
url https://arxiv.org/abs/2403.02830