# tetrahedron

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## tetrahedron:

see polyhedronpolyhedron
, closed solid bounded by plane faces; each face of a polyhedron is a polygon. A cube is a polyhedron bounded by six polygons (in this case squares) meeting at right angles.
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## Tetrahedron

A polygon with four plane surfaces.

## Tetrahedron

(or triangular pyramid), a polyhedron with four triangular faces, six edges, and four vertices. At each vertex three edges intersect. The regular tetrahedron (Figure 1) is one

Figure 1

of the five regular polyhedrons. If a is the length of an edge of a regular tetrahedron, the volume of the tetrahedron is .

## tetrahedron

[‚te·trə′hē·drən]
(crystallography)
An isometric crystal form in cubic crystals, in the shape of a four-faced polyhedron, each face of which is a triangle.
(mathematics)
A four-sided polyhedron.

## tetrahedron

A device to indicate wind direction, and, in turn, landing direction. It is tetrahedronshaped—four triangular sides. This device is generally located at uncontrolled airports. The small end of a tetrahedron points in the direction of landing. At controlled airports, the tetrahedron should be disregarded because tower instructions supercede the indicator. On approach charts, a tetrahedron is shown as.

## tetrahedron

1. a solid figure having four plane faces. A regular tetrahedron has faces that are equilateral triangles
2. any object shaped like a tetrahedron
References in periodicals archive ?
A fluorescence "turn-on" sensor for multiple analytes: OAc- F- triggered fluorogenic detection of Zn2+ in a co-operative fashion, Tetrahedron, 73, 5418 (2017).
The concepts of Safety, Quality, and Evidence are integral to all four levels, and are represented as three sides of a tetrahedron. The goals of individualized professional self-determination are positive patient outcomes and healthcare outcomes resulting from safe, quality, and evidenced-based nursing practice decisions.
The order that the three [Na.sup.+] in Mt exchanged by [C.sub.4][mim.sup.+] related to the free energy between [Na.sup.+] and silicon-oxygen tetrahedron. The closest distance between [Na.sup.+] on the right ([Na.sup.+]-1) and oxygen of silicon-oxygen tetrahedron is 2.423 [Angstrom] (Figure 3(a)), which is the longest one.
Since SWG is defined in pairs for the conformal element which shares the same face, it is important and necessary to find the tetrahedron pairs efficiently before the simulation process.
Above trends could be obtained from the results of samples A and B, supporting the catalytic property of M[O.sub.4] tetrahedron is superior to that of M[O.sub.6] octahedron.
Banerjee, "Ionic liquid promoted interrupted Feist-Benary reaction with high diastereoselectivity," Tetrahedron Letters, vol.
Information of tetrahedron mesh models Tetra Model Number of Number of Number of Name Node Spring Face Sphere 1 4K 23K 8K Sphere 2 1K 11.3K 2K Table 2.
After this stage, each individual node collates obtained measurements and performs search through existing database to identify such connecting NNs, that at least a single tetrahedron can be formed.
The vertices of the end-effector are treated as the top vertex of the tetrahedron. The space composed of eight ropes is divided into four tetrahedrons based on the tetrahedron lemma [36].
If one creates an array of tetrahedrons with 10 tetrahedrons forming a triangular base, then adding 6 tetrahedrons to form the next level up, followed by 3 tetrahedrons at the third level up and finally a single tetrahedron at the fourth level at the top, one creates a larger, stable tetrahedral structure called an isotropic vector matrix (21,24).
With a nominal 2-year mission, the quartet will fly 10 km (6.2 miles) apart from one another in a tetrahedron formation, with positions accurate to 100 meters.
For example, the little-known British geologist and former president of the Geological Society of London, John Walter Gregory, used the newly accurate maps to suggest that the Earth was contracting into the shape of a tetrahedron. He claimed that three supposed landmasses were evident in these maps (the Americas, Europe-Africa, and Asia-Australasia), constituting the edges of the tetrahedron (with the apex in the Arctic and base in Antarctica), while the three major oceans (the Atlantic, Pacific and Indian) formed the faces.

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