Raoul Bricard (23 March 1870 – 26 November 1943) was a French engineer and a mathematician. He is best known for his work in geometry, especially descriptive geometry and scissors congruence, and kinematics, especially mechanical linkages.
Biography Bricard taught geometry at Ecole Centrale des Arts et Manufactures. In 1908 he became a professor of applied geometry at the National Conservatory of Arts and Crafts in Paris.Science, vol. 28 (1908), p. 707. In 1932 he received the Poncelet Prize in mathematics from the Paris Academy of Sciences for his work in geometry."Prize Awards of the Paris Academy of Sciences", Nature vol. 131 (1933) 174-175.
Work In 1896 Bricard published a paper on Hilbert's third problem, even before the problem was stated by Hilbert.R. Bricard, "Sur une question de géométrie relative aux polyèdres", Nouvelles annales de mathématiques, Ser. 3, Vol. 15 (1896), 331-334. In it he proved that mirror symmetric polytopes are scissors congruent, and proved a weak version of Dehn's criterion.
In 1897 Bricard published an important investigation on flexible polyhedra.R. Bricard, Mémoire sur la théorie de l’octaèdre articulé , J. Math. Pures Appl., Vol. 3 (1897), 113–150 (see also the English translation and an alternative scan). In it he classified all flexible octahedra, now known as Bricard octahedra.P. Cromwell, Polyhedra, Cambridge University Press, 1997. This work was the subject of Henri Lebesgue's lectures in 1938. Later Bricard discovered notable 6-bar linkages.K. Wohlhart, The two types of the orthogonal Bricard linkage, Mechanism and machine theory, vol. 28 (1993), 809-817..
Bricard also gave one of the first geometric proofs of Morley's trisector theorem in 1922.Alain Connes, "Symmetries", European Mathematical Society Newsletter No. 54 (December 2004).
Books Bricard authored six books, including a mathematics survey in Esperanto.Raoul Bricard, from Open Library. He is listed in Encyclopedia of Esperanto.Encyclopedia of Esperanto Matematika terminaro kaj krestomatio (in Esperanto), Hachette, Paris, 1905 Géométrie descriptive, O. Doin et fils, 1911 Cinématique et mécanismes, A. Colin, 1921 Petit traité de perspective, Vuibert, 1924 Leçons de cinématique, Gauthier-Villars et cie., 1926 Le calcul vectoriel, A. Colin, 1929
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References Laurent R., Raoul Bricard, Professeur de Géométrie appliquée aux arts, in Fontanon C., Grelon A. (éds.), Les professeurs du Conservatoire national des arts et métiers, dictionnaire biographique, 1794-1955, INRP-CNAM, Paris 1994, vol. 1, pp. 286–291.
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