Today, no less than in the past, the tetrahedral form of the earth and the relation of the tetrahedron to the poles and to the equator preserve the conditions that favor rapid evolution.
Each of the four depressed areas forms a side of our tetrahedron and is occupied by an ocean.
If six films of the same liquid meet in a point the corresponding tetrahedron is a regular tetrahedron, and each film, where it meets the others, has an angle whose cosine is -1/3.
The fact cannot rest unobserved, that mica has only one laminar cleavage, feldspar two, quartz three, this being for the first time a perfect crystal, a double tetrahedron with one column.
Diagrams for comparison of coasts upon an upright and upon an inverted tetrahedron 17 7.
The form toward which the figure of the earth is tending, a tetrahedron with symmetrically truncated angles.
Of all regular figures with plane surfaces the tetrahedron has the smallest volume for a given surface, and it presents moreover a reciprocal relation of projection to depression.
A truncated tetrahedron to show the reciprocal relation of projection and depression upon the surface 13 5.
Assuming the four valencies of the carbon atom to be directed from the centre of a regular tetrahedron towards its four corners, the angle at which they meet is 109 deg.
We may therefore regard the nitrogen atoms as occupying the centres of a cubic space lattice composed of iodine atoms, between which the hydrogen atoms are distributed on the tetrahedron face normals.
Their habit varies according to whether the tetrahedron (fig.
Penetration twins with a tetrahedronface as twin-plane are sometimes observed.
It is generated by the lines which cut the faces of a tetrahedron in a constant cross ratio, and therefore by those subtending the same cross ratio at the four vertices.
A tetrahedron self-conjugate with respect to the absolute has all its intersecting elements (edges and planes) at right angles.
The singular surface is made up of the faces or the vertices of the fundamental tetrahedron, and each edge of this tetrahedron is a double line of the complex.
Pertaining or related to a tetrahedron, or to the system of hemihedral forms to which the tetrahedron belongs.
Note: In crystallography, the regular tetrahedron is regarded as the hemihedral form of the regular octahedron.
In crystallography, the regulartetrahedron is regarded as the hemihedral form of the regular octahedron.
In the first case all four spines are equal, and diverge from a common central point at equal angles in different directions, corresponding to the four axes of a regular tetrahedron (Tetraplagia and Tetraplecta, Pl.
The skeleton is composed of four radial rods, diverging from one common centre in different directions, and corresponding to the four axes, which extend from the central point of a tetrahedron to the central points of its four faces.
If this be so the form of the diamond is really the tetrahedron (and the various figures derived symmetrically from it) and not the octahedron.
If the grooves be left out of account, the large faces which have replaced each tetrahedron corner then make up a figure which has the aspect of a simple octahedron.
The tetrahedron was assigned to fire, the octahedron to air, the icosahedron to water, and the cube to earth, it being asserted that the smallest constituent part of each of these substances had the form here assigned to it.
It is not difficult for a class to find the relative areas of the cube and the inscribed tetrahedron and octahedron.
The figure is difficult to draw, but it is not difficult to understand, particularly if we construct the tetrahedron out of pasteboard.
The hemihedral form {hkk} of the icositetrahedron; it is bounded by twelve isosceles triangles arranged in threes over the tetrahedron faces.
This is bounded by four equilateral triangles and is identical with the regulartetrahedron of geometry.
By reflection across the six dodecahedral planes of symmetry a tetrahedron only would result, but if this is associated with a centre of symmetry we obtain the octahedron.
Above thetetrahedron is a balloon-shaped figure, apparently drawn into shape by the attraction of the tetrahedron.
The tetrahedron is not confined to the external form of the above atoms; it seems to be one of the favourite forms of nature, and repeatedly appears in the internal arrangements.
The same characteristics of four funnels opening on the faces of a tetrahedron are found in all, but magnesium and sulphur have no central globe, and in cadmium and tellurium the globe has become a cross.
We here meet the tetrahedron for the first time, with each angle occupied by a six-atomed group, the atoms arranged as on the end triangles of a prism.
As a proto-element it becomes three triangles, joined at their apices, in fact a tetrahedron in which no atoms are distributed on the fourth face.
The tetrahedron is the form of chromium and molybdenum, but not that of the head of their group, oxygen, which is, like hydrogen, sui generis.
Illustration] It will be seen that the tetrahedron is the fundamental form, the three-sided pyramid on a triangular base, i.
In the tetrahedron four funnels are found, the mouth of each funnel opening on one of its faces.
The "cigar" tetrahedron of d follows its course as in occultum, and the other sets free two quartets and two triplets on the meta level, yielding six duads and two units as hyper compounds.
From the new vertex there is also a tetrahedron resting upon each base of the original tetrahedron so that there are five tetrahedra in all.
At the vertices of a regular tetrahedron may be found such points.
The tetrahedron has four points, one at each vertex, 6 lines and 4 equilateral triangles, as in Fig.
This four dimensional figure may be generated by moving the tetrahedron in the direction of the fourth dimension, as in Fig.
If a plane be passed through each of the six edges of the tetrahedron and the new vertex there will be six new planes or faces, making 10 in all, counting the original four.
As particular cases: the mass-centre of a uniform thin triangular plate coincides with that of three equal particles at the corners; and that of a uniform solid tetrahedron coincides with that of four equal particles at the vertices.
Kailas turns a sharp edge to the north, and from here the peak resembles a tetrahedron more than ever.
In form it resembles a tetrahedron set on a prism.
A tetrahedron is equivalent to the third of the triangular prism of the same base and the same height.
The volume of a tetrahedron and that of any pyramid are measured by the third of the product of the base by the height.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "tetrahedron" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: figure; foursome; quadrangle; quartet; quaternary; rectangle; square; squaring; triangle
