Crossword clues for tetrahedron
The Collaborative International Dictionary
Tetrahedron \Tet`ra*he"dron\, n. [Tetra- + Gr. ? seat, base, fr. ? to sit.] (Geom.) A solid figure inclosed or bounded by four triangles.
Note: In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron.
Regular tetrahedron (Geom.), a solid bounded by four equal equilateral triangles; one of the five regular solids.
Douglas Harper's Etymology Dictionary
"triangular pyramid, solid figure contained by four triangular surfaces," 1560s, from Late Greek tetraedron, noun use of neuter of tetraedros (adj.) "four-sided," from tetra- "four" (see tetra-) + hedra "seat, base, chair, face of a geometric solid," from PIE root *sed- (1) "to sit" (see sedentary). Related: Tetrahedral.
Wiktionary
n. (context geometry English) a polyhedron with four faces; the regular tetrahedron, the faces of which are equal equilateral triangles, is one of the Platonic solids.
WordNet
n. any polyhedron having four plane faces
[also: tetrahedra (pl)]
Wikipedia
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons) is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ordinary convex polyhedra and the only one that has fewer than 5 faces.
The tetrahedron is the three-dimensional case of the more general concept of a Euclidean simplex.
The tetrahedron is one kind of pyramid, which is a polyhedron with a flat polygon base and triangular faces connecting the base to a common point. In the case of a tetrahedron the base is a triangle (any of the four faces can be considered the base), so a tetrahedron is also known as a "triangular pyramid".
Like all convex polyhedra, a tetrahedron can be folded from a single sheet of paper. It has two such nets.
For any tetrahedron there exists a sphere (called the circumsphere) on which all four vertices lie, and another sphere (the insphere) tangent to the tetrahedron's faces.
Tetrahedron is a weekly peer-reviewed scientific journal covering the field of organic chemistry. According to the Journal Citation Reports, the journal has a 2014 impact factor of 2.641. Tetrahedron and Elsevier, its publisher, support an annual symposium.
Usage examples of "tetrahedron".
They must have counted on taking the Tangoparu tetrahedron completely by surprise, wiping out the original four and all the newer resonators with sabotage or gazer strikes.
Then she drew from it a small packet formed by folding a bamboo leaf into a tetrahedron and tucking in the ends.
Obviously, such retroactive witchcraft was worthy of further investigation, and the key was the synergetic geometry of the Fuller tetrahedron in which he had kept his manikin during the spell-casting.
From the apex of the tetrahedron rose the king post, a specially fabricated compound member exactly analogous to the backbone of a vertebrate animal.
The Ekhat ship resembled two tetrahedrons oriented in opposition to one another, with an immense and lumpy almost-pyramid close to what would have been its center.
Cat was beginning to berate herself for letting him rob her when he returned with two fat, fresh rice cakes wrapped in bamboo leaves artistically formed into tetrahedrons, and a small packet of pickled radish.
The Humvee drove over a vehicle-trap mechanism buried in the roadway, then turned carefully through four enormous concrete tetrahedrons planted in the road as crash barriers.
Then, in a near miraculous find, they rescued a few metal tetrahedrons from deep trenches that had once been the coast of a continent.
Stored in the atoms of the tetrahedrons were the histories of both civilizations.
We shall do the same: we shall not attempt to give the reader any idea of that tetrahedron nose, of that horseshoe mouth, of that little left eye, stubbled up with an eyebrow of carrotty bristles, while the right was completely overwhelmed and buried by an enormous wen.
Each atom is covalently bonded to four neighbors to form the corners of a tetrahedron, a solid figure with four three-sided faces.
Behind me, the flyers broke from the circling holding pattern we had maintained for our conference to form the tetrahedron behind me.
Four colored spheres the size of marbles hung on crystal rods arranged with respect to each other as the four major axes of a tetrahedron.
The effect was as though one were looking down at the apex of a regular tetrahedron.
The Lunar system was the simplest, with just four entry points set at the vertices of a regular tetrahedron.