noun
definition
A solid figure with many flat faces and straight edges.
definition
A polyscope, or multiplying glass.
Examples of polyhedron in a Sentence
More briefly, the figure may be defined as a polyhedron with two parallel faces containing all the vertices.
Probably the best way to make a sphere is to make a polyhedron with a large number of sides.
The points thus obtained are evidently the vertices of a polyhedron with plane faces.
Each stage of refinement defines a new, denser, polyhedron whose vertices are related to local sets of vertices of the original.
In the first place, each of these figures may be conceived as an orthogonal projection of a closed plane-faced polyhedron.
In origami this term is often misused to mean any star-like form produced by adding pyramids to the faces of a convex polyhedron.
The head of this list is iteratively decimated and the list updated until a target number of vertices for the sparse polyhedron is met.
One needs to select all atoms in the cage - these will be the vertices of the final polyhedron.
Clerk Maxwell, who showed amongst other things that a reciprocal can always be drawn to any figure which is the orthogonal projection of a plane-faced polyhedron.
Normally by the end of the calculation less than one half of the entries in BOX actually are used to define the limiting polyhedron.
The "regular icosahedron" is one of the Platonic solids; the "great icosahedron" is a Kepler-Poinsot solid; and the "truncated icosahedron" is an Archimedean solid (see Polyhedron).
The "ordinary dodecahedron" is one of the Platonic solids (see Polyhedron).
The "small stellated dodecahedron," the "great dodecahedron" and the "great stellated dodecahedron" are Kepler-Poinsot solids; and the "truncated" and "snub dodecahedra" are Archimedean solids (see Polyhedron).
This is one of the Platonic solids, and is treated in the article Polyhedron, as is also the derived Archimedean solid named the "truncated tetrahedron"; in addition, the regular tetrahedron has important crystallographic relations, being the hemihedral form of the regular octahedron and consequently a form of the cubic system.
If the figure be entirely to one side of any face the polyhedron is said to be " convex, " and it is obvious that the faces enwrap the centre once; if, on the other hand, the figure is to both sides of every face it is said to be concave, " and the centre is multiply enwrapped by the faces.
The mensuration of the cube, and its relations to other geometrical solids are treated in the article Polyhedron; in the same article are treated the Archimedean solids, the truncated and snubcube; reference should be made to the article Crystallography for its significance as a crystal form.
A polyhedron is said to be the hemihedral form of another polyhedron when its faces correspond to the alternate faces of the latter or holohedral form; consequently a hemihedral form has half the number of faces of the holohedral form.
The correspondence of the faces of polyhedra is also of importance, as may be seen from the manner in which one polyhedron may be derived from another.
If we take any polyhedron with plane faces, the null-planes of its vertices with respect to a given wrench will form another polyhedron, and the edges of the latter will be conjugate (in the above sense) to those of the former.
Octahedra having triangular faces other than equilateral occur as crystal forms. See Polyhedron and Crystallography.