The Steiner-Lehmus Theorem has garnered much attention since its conception in the 1840s. A variety of proofs resulting from the posing of the theorem are still appearing today, well over 100 years later. There are some amazing similarities among these proofs, as different as they seem to be. These characteristics allow for some interesting groupings and observations.

Made available in DSpace on 2016-04-27T16:57:20Z (GMT). No. of bitstreams: 1 Gilson Bispo de Jesus.pdf: 2003628 bytes, checksum: b76e6d0b8ebbf82f910e9ece19c3d41a (MD5) Previous issue date: 2012-10-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis deals with the Instrumental Genesis, which is the preparation process of instrument by the subject. Studies on national and international levels have addressed this process, however, no studies that dealt with Instrumental Genesis referring to an abstract artifact were found. This research revealed the bisector as an abstract artifact. Thus, the goals were to analyze based on the actions of two teachers as the bisector artifact becomes an instrument to solve geometric problems, and investigate how this process could contribute to the learning of geometry by these teachers. Based on these objectives, the research conducted answered the following research questions: how the bisector of Instrumental Genesis happens when the subject interacts with this mathematical object to solve a geometric problem? How the insertion of a bisector mathematical object may interfere in the geometric content learning process by the subject? The methodological choice was the case study that contributed to the achievement of research objectives and the studies those carried out regarding Theory of Instrumentation and Anthropological Theory of Didactics which provided the theoretical elements appropriate for this research. The task, techniques and theoretical-technological discourse analysis enabled to perceive the various instruments developed by teachers while they organized their actions. Furthermore, the didactic organization enabled teachers to develop different techniques supported in the theoretical-technological discourse by solving geometric construction tasks proposed in this organization. The process of Instrumental Genesis of bisector was found in the teachers actions, since these actions emphasized the mobilization and/or construction of various use schemes that were added to this mathematical object. At the same time, this process contributed to the learning mediated by bisector of some topics of Plane Geometry / Esta tese trata da Gênese Instrumental, que consiste no processo de elaboração do instrumento pelo sujeito. Estudos em níveis nacionais e internacionais já abordaram esse processo; no entanto, não foram encontrados trabalhos que tratassem da Gênese Instrumental, tomando como referência um artefato abstrato. Nesta pesquisa, evidenciou-se a mediatriz como artefato desse tipo. Assim, seus objetivos foram analisar com base nas ações de dois professores, como o artefato mediatriz transforma-se em instrumento na resolução de problemas geométricos e investigar como esse processo poderia contribuir para a aprendizagem de conteúdos geométricos por parte desses professores. Com base nesses objetivos, a pesquisa realizada respondeu às seguintes questões de investigação: de que modo acontece a Gênese Instrumental da mediatriz, quando o sujeito interage com esse objeto matemático na resolução de problemas geométricos? Como a inserção do objeto matemático mediatriz interfere no processo de aprendizagem de conteúdos geométricos por parte do sujeito? A escolha metodológica foi o estudo de caso que contribuiu para o alcance dos objetivos da pesquisa e os estudos realizados a respeito da Teoria da Instrumentação e da Teoria Antropológica do Didático forneceram os elementos teóricos apropriados para esta pesquisa. A análise das tarefas, das técnicas e do discurso tecnológico-teórico fez perceber os vários instrumentos elaborados pelos professores, quando eles organizavam suas ações. Além disso, a organização didática favoreceu que os professores desenvolvessem técnicas diferentes apoiadas no discurso tecnológico-teórico, ao solucionarem as tarefas de construção geométrica propostas nessa organização. Constatou-se, nas ações dos professores, o processo de Gênese Instrumental da mediatriz, visto que essas ações evidenciaram a mobilização e/ou a construção de vários esquemas de utilização que foram agregados a este objeto matemático. Ao mesmo tempo, esse processo contribuiu para a aprendizagem mediada pela mediatriz de alguns tópicos de Geometria Plana

The present thesis contributes to the theory of generalized Minkowski spaces as a continuation of Minkowski geometry, i.e., the geometry of finite-dimensional normed spaces over the field of real numbers. In a generalized Minkowski space, distance and length measurement is provided by a gauge, whose definition mimics the definition of a norm but lacks the symmetry requirement. This seemingly minor change in the definition is deliberately chosen. On the one hand, many techniques from Minkowski spaces can be adapted to generalized Minkowski spaces because several phenomena in Minkowski geometry simply do not depend on the symmetry of distance measurement. On the other hand, the possible asymmetry of the distance measurement set up by gauges is nonetheless meaningful and interesting for applications, e.g., in location science. In this spirit, the presentation of this thesis is led mainly by minimization problems from convex optimization and location science which are appealing to convex geometers, too. In addition, we study metrically defined objects, which may receive a new interpretation when we measure distances asymmetrically. To this end, we use a combination of methods from convex analysis and convex geometry to relate the properties of these objects to the shape of the unit ball of the generalized Minkowski space under consideration.

Chapter 1 presents the definitions and basic properties of trigonometric functions including: Sum Identities, Difference Identities, Product-Sum Identities and Sum-Product Identities. These formulas provide effective tools to solve the problems in trigonometry. Chapter 2 handles the most important two theorems in trigonometry: The laws of sines and cosines and show how they can be applied to derive many well known theorems including: Ptolemy¡¦s theorem, Euler Triangle Formula, Ceva¡¦s theorem, Menelaus¡¦s Theorem, Parallelogram Law, Stewart¡¦s theorem and Brahmagupta¡¦s Formula. Moreover, the formulas of computing a triangle area like Heron¡¦s formula and Pick¡¦s theorem are also discussed. Chapter 3 deals with the method of superposition, inverse trigonometric functions, polar forms and De Moivre¡¦s Theorem.