About the determination of the center and axis of a direct similarity in 3D

• Autores: Eugenio Roanes Macías
• Localización: Boletín de la Sociedad Puig Adam de profesores de matemáticas, ISSN 1135-0261, Nº. 108, 2019 (Ejemplar dedicado a: Profesor Joaquín Hernández Gómez), págs. 57-72
• Idioma: inglés
• Títulos paralelos:
  • Sobre la determinación del centro y el eje de una semejanza directa en 3D
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• Resumen

  • A 3D direct similarity defined by a tetrahedron and its image tetrahedron of proportional edges is considered. This similarity is a "dilative rotation", consisting of a rotation around an axis and a stretch with center in the rotation axis. Methods of synthetic geometry are used in this paper for determining such center and axis. Finally, methods of elementary analytic geometry with matrix calculus are used for solving concrete examples in a brief way.