Poliedros de Kepler-Poinsot: uma verificação da relação de Euler com jujubas, canudos e varetas.
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Data
2018-08-03
Autores
Baraldi, Marcos Luchiari
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Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho apresenta uma verificação de uma das relações mais importantes da matemática elementar: a relação de Euler. Ela expressa uma relação entre o número vértices, arestas e faces de poliedros convexos, podendo ser estendida aos poliedros estrelados, particularmente aos de Kepler-Poinsot. Para analisar tal relação, a proposta é utilizar material concreto, como jujubas, canudos e varetas de fibra. A princípio é realizada a construção dos poliedros de Platão, canudos rígidos e coloridos, onde é possível verificar com facilidade a veracidade da Relação de Euler. Na sequência utilizam-se as varetas de fibra de vidro 1,4 mm que com a introdução nas arestas dos poliedros, verifica-se facilmente que apenas o dodecaedro e o icosaedro são passíveis da estrelação, por prolongamento das arestas obtendo assim, dois dos poliedros estrelados de Kepler-Poinsot. Por fim, é analisado que a Relação de Euler, também se verifica para esses estrelados. Com tal procedimento fica mais perceptível a não existência de outros poliedros estrelados, pois a partir de sua construção com canudos e a ampliação de suas arestas com varetas fica claro a não intersecção delas. Vale lembrar que tais atividades lúdicas são incentivadas no ensino da matemática e algumas já foram abordadas em dissertações do PROFMAT e em documentos oficiais de ensino no Brasil, como nos Parâmetros Curriculares Nacionais, no Currículo do Estado de São Paulo, matrizes de referências de avaliações tais como: Saresp (Sistema de avaliação de rendimento escolar do estado de São Paulo), Saeb (Sistema nacional de avaliação do ensino básico) e ENEM (Exame nacional do ensino médio).
This paper presents a verification of one of the most important relations of elementary mathematics: Euler's relation. It expresses a relation between the number of vertices, edges and faces of convex polyhedra, and can be extended to the starry polyhedra, particularly to those of Kepler-Poinsot. To analyze this relationship, the proposal is to use concrete material, such as jelly beans, straws and fiber rods. At first the construction of Plato's polyhedrons, rigid and colored straws, is carried out, where it is possible to verify with ease the veracity of the Euler Relation. The 1.4 mm glass fiber rods are then used which, with the introduction of polyhedron edges, can easily be verified that only the dodecahedron and the icosahedron are capable of staring by prolonging the edges, thus obtaining two of the polyhedra starring Kepler-Poinsot. Finally, it is analyzed that the relation of Euler, also is verified for these stars. With such a procedure it is more noticeable the existence of other starry polyhedra, since from its construction with straws and the enlargement of its edges with rods it is clear the nonintersection of them. It is worth remembering that such play activities are encouraged in the teaching of mathematics and some have already been addressed in PROFMAT dissertations and in official teaching documents in Brazil, such as in the National Curriculum Parameters, in the Curriculum of the State of São Paulo, references reference matrices such as: Saresp (System of evaluation of school performance of the state of São Paulo), Saeb (National system of evaluation of basic education) and ENEM (National High School Examination).
This paper presents a verification of one of the most important relations of elementary mathematics: Euler's relation. It expresses a relation between the number of vertices, edges and faces of convex polyhedra, and can be extended to the starry polyhedra, particularly to those of Kepler-Poinsot. To analyze this relationship, the proposal is to use concrete material, such as jelly beans, straws and fiber rods. At first the construction of Plato's polyhedrons, rigid and colored straws, is carried out, where it is possible to verify with ease the veracity of the Euler Relation. The 1.4 mm glass fiber rods are then used which, with the introduction of polyhedron edges, can easily be verified that only the dodecahedron and the icosahedron are capable of staring by prolonging the edges, thus obtaining two of the polyhedra starring Kepler-Poinsot. Finally, it is analyzed that the relation of Euler, also is verified for these stars. With such a procedure it is more noticeable the existence of other starry polyhedra, since from its construction with straws and the enlargement of its edges with rods it is clear the nonintersection of them. It is worth remembering that such play activities are encouraged in the teaching of mathematics and some have already been addressed in PROFMAT dissertations and in official teaching documents in Brazil, such as in the National Curriculum Parameters, in the Curriculum of the State of São Paulo, references reference matrices such as: Saresp (System of evaluation of school performance of the state of São Paulo), Saeb (National system of evaluation of basic education) and ENEM (National High School Examination).
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Aprendizagem matemática, Material concreto, Relação de Euler, Poliedros de Kepler-Poinsot, Learning Mathematics, Concrete material, Euler relation, Kepler-Poinsot polyhedra