• East Asian mathematical journal
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• v.30 no.3
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• pp.303-310
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• 2014

We study the existence of regular polygons and regular solids whose vertices have integer coordinates in the three dimensional space and study side lengths of such squares, cubes and tetrahedra. We show that except for equilateral triangles, squares and regular hexagons there is no regular polygon whose vertices have integer coordinates. By using this, we show that there is no regular icosahedron and no regular dodecahedron whose vertices have integer coordinates. We characterize side lengths of such squares and cubes. In addition to these results, we prove Ionascu's result [4, Theorem2.2] that every equilateral triangle of side length $\sqrt{2}m$ for a positive integer m whose vertices have integer coordinate can be a face of a regular tetrahedron with vertices having integer coordinates in a different way.

• School Mathematics
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• v.9 no.2
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• pp.277-289
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• 2007

This research aims to look into the mathematically gifted 6th and 7th graders spatial visualization ability of solid figures. The subjects of the research was six male elementary school students in the 6th grade and one male middle school student in the 1th grade receiving special education for the mathematically gifted students supported by the government. The task used in this research was the problems that compares the side lengths and the angle sizes in 4 pictures of its two dimensional representation of a regular icosahedron. The data collected included the activity sheets of the students and in-depth interviews on the problem solving. Data analysis was made based on McGee's theory about spatial visualization ability with referring to Duval's and Del Grande's. According to the results of analysis of subjects' spatial visualization ability, the spatial visualization abilities mainly found in the students' problem-solving process were the ability to visualize a partial configuration of the whole object, the ability to manipulate an object in imagination, the ability to imagine the rotation of a depicted object and the ability to transform a depicted object into a different form. Though most subjects displayed excellent spatial visualization abilities carrying out the tasks in this research, but some of them had a little difficulty in mentally imagining three dimensional objects from its two dimensional representation of a solid figure.