A triangle, square or pentagon.
A triangle, square or pentagon.
triangles and pentagons
A regular octahedron is one of the platonic solids. Each of its faces is an equilateral triangle.
The quick answer: because of the high degree of symmetry inherent in the Platonic solids. They are vertex-uniform, edge-uniform and face-uniform. If you hold several models of the same shape up by any vertex, all the models will appear the same. The same goes for holding the models up by any edge, or by any face. Read the following for a little more detail. Many solids that are not Platonic have symmetry as well, but the Platonic solids have some special symmetrical properties. You can create what are called 'dual polyhedrons' for solids, but the duals for Platonic solids are unique. You can form a Platonic solid's dual polyhedron by making the midpoint of every face of the original Platonic solid a vertex of the dual solid within the original. If you start with a cube, a hexahedron really, and make a new solid within it having vertexes at the centers of the square faces of the cube, the solid within will be an octahedron. Tetrahedrons are self-dual, squares and octahedrons are dual with one another, and dodecahedrons and icosahedrons are dual with one another. The dual polyhedron of a Platonic solid is always another Platonic solid. This is difficult to visualize without aid. See link for some clarification. On the dual relationship of a cube [6 faces, 8 vertexes] and octahedron [8 faces, 6 vertexes] breaking down the numbers of faces and vertexes might help. Each of the 6 faces of a cube contains one of the vertexes of the octahedron, and each of the vertexes of a cube will be at the center of one of the faces of the octahedron.
A cubeoid is not a platonic solid because it does not have equal edges and angles like a platonic solid. Platonic solids have regular polygon faces where each face, edge, and vertex is the same. Cubeoids have rectangular faces and unequal edges and angles.
equilateral triangles and regular pentagons
A platonic solid is a special kind of polyhedron. A polyhedron is a 3-D figure whose faces are polygons.In a platonic solid all faces are identical regular polygons. A polyhedron has faces, edges, and vertices. The numbers of each are related by Euler's formula, V+F=E+2
A triangle, square or pentagon.
A triangle, square or pentagon.
A Platonic solid is a solid all of whose face are regular and congruent polygons.There are five of these:A Tetrahedron. Four faces, each an equilateral triangle.Ad InfoA Hexahedron (Cube). Six faces, each a square.An Octahedron. Eight faces, each an equilateral triangle.A Dodecahedron. Twelve faces, each a regular pentagon.An Icosahedron. Twenty faces, each an equilateral triangle.
triangles and pentagons
The 7-faced solid is called a "hexagonal pyramid."
tetrahedron
A solid with a regular polygon for each face is known as a perfect solid.
A regular octahedron is one of the platonic solids. Each of its faces is an equilateral triangle.
6 faces , including 5 triangles and one hexagon . :)