About the determination of the center and axis of a direct similarity in 3D
ISSN: 1135-0261
Year of publication: 2019
Issue Title: Profesor Joaquín Hernández Gómez
Issue: 108
Pages: 57-72
Type: Article
More publications in: Boletín de la Sociedad Puig Adam de profesores de matemáticas
Abstract
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.