The 'form' of a triangle

Autor: Alain Chenciner
Jazyk: English<br />French<br />Italian
Rok vydání: 2007
Předmět:
Zdroj: Rendiconti di Matematica e delle Sue Applicazioni, Vol 27, Iss 1, Pp 1-16 (2007)
Druh dokumentu: article
ISSN: 1120-7183
2532-3350
Popis: Heron’s formula, maybe due to Archimedes, expresses the squared area of a triangle as a polynomial in the squared lengths of its sides. A true understanding of this formula comes from an adequate coding of the shape of a triangle, i.e. of the triangle up to translations, rotations and reflexions. One can then build a “space of triangle shapes” which, if orientation is added becomes the “shape sphere” and possesses very nice symmetries which were recently used in researches on the 3-body problem. The invariant interpretation of the shape sphere in turn sheds light on the nature of Heron’s formula.
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