Как найти площадь поверхности правильного додекаэдра

Правильный додекаэдр
(вращающаяся модель, 3D-модель)
Тип	правильный многогранник
Свойства	выпуклый
Комбинаторика
Элементы	12 граней 30 рёбер 20 вершин Χ = 2
Грани	правильные пятиугольники
Конфигурация вершины	53
Двойственный многогранник	правильный икосаэдр
Вершинная фигура
Развёртка
Классификация
Обозначения	U23, C26, W5
Символ Шлефли	{5,3}
Символ Витхоффа[en]	3 | 2 5
Диаграмма Дынкина
Группа симметрии	Ih, H3, [5,3], (*532)
Группа вращения	I, [5,3]+, (532)
Количественные данные
Длина ребра
Площадь поверхности
Объём
Двугранный угол
Телесный угол при вершине
Медиафайлы на Викискладе

Пра́вильный додека́эдр (др.-греч. δωδεκάεδρον, от δώδεκα — «двенадцать» и ἕδρα — «грань») — один из пяти возможных правильных многогранников. Додекаэдр составлен из двенадцати правильных пятиугольников^[1], являющихся его гранями. Каждая вершина додекаэдра является вершиной трёх правильных пятиугольников. Таким образом, додекаэдр имеет 12 граней (пятиугольных), 30 рёбер и 20 вершин (в каждой сходятся 3 ребра).

История[править | править код]

Пожалуй, самый древний предмет в форме додекаэдра был найден в северной Италии, около Падуи, в конце XIX века, он датируется 500 г. до н. э. и предположительно использовался этрусками в качестве игральной кости^[2][3].

Додекаэдр рассматривали в своих сочинениях древнегреческие учёные. Платон сопоставлял с правильными многогранниками различные классические стихии. О додекаэдре Платон писал, что «…его бог определил для Вселенной и прибегнул к нему в качестве образца»^[4]. Евклид в предложении 17 книги XIII «Начал» строит додекаэдр на рёбрах куба^{[5][6]:132-136}. Папп Александрийский в «Математическом собрании» занимается построением додекаэдра, вписанного в данную сферу, попутно доказывая, что вершины додекаэдра лежат в параллельных плоскостях^{[7][6]:318-319[8]}.

На территории нескольких европейских стран найдено множество предметов, называемых римскими додекаэдрами, относящихся ко II—III вв. н. э., назначение которых не совсем понятно.

Вскоре после появления кубика Рубика, в 1981 году была запатентована подобная головоломка в форме правильного додекаэдра — мегаминкс. Как и у классического кубика Рубика, к каждому ребру у неё прилегает по три детали^[9]. Позднее, как и для кубика Рубика появились такие додекаэдрические головоломки с четырьмя деталями при ребре (гигаминкс), пятью (тераминкс) и т.д. Сложность и время сборки их, как и для кубика Рубика возрастает по мере увеличения числа деталей при ребре.

Основные формулы[править | править код]

Если за длину ребра принять , то площадь поверхности додекаэдра равна

Объём додекаэдра

Радиус описанной сферы^[10]

Радиус полувписанной сферы равен ^[10]

Радиус вписанной сферы^[10]

Свойства[править | править код]

• Все двадцать вершин додекаэдра лежат по пять в четырёх параллельных плоскостях, образуя в каждой из них правильный пятиугольник.
• Двугранный угол между любыми двумя смежными гранями додекаэдра равен arccos(−1/√5) ≈ 116,565°^[10].
• Сумма плоских углов при каждой из 20 вершин равна 324°, телесный (трёхгранный) угол равен arccos(−11/5√5) ≈ 2,9617 стерадиана.
• В додекаэдр можно вписать куб так, что стороны куба будут диагоналями додекаэдра.
• Додекаэдр имеет три звёздчатые формы.
• В додекаэдр можно вписать пять кубов. Если заменить пятиугольные грани додекаэдра плоскими пятиугольными звездами так, что исчезнут все рёбра додекаэдра, то получим пространство пяти пересекающихся кубов. Додекаэдр как таковой исчезнет. Вместо замкнутого многогранника появится открытая геометрическая система пяти ортогональностей. Или симметричное пересечение пяти трёхмерных пространств.
• Ближайшая параллельная к произвольно выбранной грани плоскость, в которой лежат пять вершин, не принадлежащих выбранной грани, отстоит от этой грани на расстояние радиуса описанной вокруг данной грани окружности. А радиус описанной вокруг этих пяти вершин окружности равен диаметру вписанной в любую из граней окружности. Эти две величины равны, соответственно, и , где — длина ребра додекаэдра.

Элементы симметрии додекаэдра[править | править код]

Связь со сферическим замощением[править | править код]

Правильный додэкаэдр также индуцирует замощение сферы правильными пятиугольниками.

Ортографическая проекция[en]	Стереографическая проекция

Интересные факты[править | править код]

• В 1887 году Эрнст Геккель описал радиолярию Circorrhegma dodecahedra, имеющую форму, близкую к додекаэдру^[11].
• в 1982 году был синтезирован додекаэдран, химическое соединение (C₂₀H₂₀) в форме додекаэдра.
• В 2003 году при анализе данных космического аппарата WMAP, была выдвинута гипотеза, что Вселенная представляет собой додекаэдрическое пространство Пуанкаре^[12][13][14].

В культуре[править | править код]

• Додекаэдр применяется как генератор случайных чисел (вместе с другими костями) в настольных ролевых играх^[15], и обозначается при этом d12 (dice — кости).
• Изготавливаются настольные календари в форме додекаэдра из бумаги, где каждый из двенадцати месяцев расположен на одной из граней^[15].
• В игре Пентакор мир представлен в виде этой геометрической фигуры^{[источник не указан 2658 дней]}.
• В играх «Sonic the Hedgehog 3» и «Sonic & Knuckles» серии Sonic the Hedgehog вид додекаэдра имеют Изумруды Хаоса^{[источник не указан 2658 дней]}.
• В игре «Destiny» форму додекаэдра имеют энграммы^{[источник не указан 2658 дней]}.
• В игре «Overwatch» персонаж Сигма при основной атаке выпускает по 2 додекаэдра^{[источник не указан 1135 дней]}.
• Пульт управления системой освещения Nanoleaf Smart Remote Control ^[16].

См. также[править | править код]

Примечания[править | править код]

Ссылки[править | править код]

• На Викискладе есть медиафайлы по теме Правильный додекаэдр

Regular dodecahedron
(Click here for rotating model)
Type	Platonic solid
Elements	F = 12, E = 30 V = 20 (χ = 2)
Faces by sides	12{5}
Conway notation	D
Schläfli symbols	{5,3}
Face configuration	V3.3.3.3.3
Wythoff symbol	3 | 2 5
Coxeter diagram
Symmetry	Ih, H3, [5,3], (*532)
Rotation group	I, [5,3]+, (532)
References	U23, C26, W5
Properties	regular, convex
Dihedral angle	116.56505° = arccos(−1⁄√5)
5.5.5 (Vertex figure)	Regular icosahedron (dual polyhedron)
Net

A regular dodecahedron or pentagonal dodecahedron is a dodecahedron that is regular, which is composed of 12 regular pentagonal faces, three meeting at each vertex. It is one of the five Platonic solids. It has 12 faces, 20 vertices, 30 edges, and 160 diagonals (60 face diagonals, 100 space diagonals).^[2] It is represented by the Schläfli symbol {5,3}.

Dimensions[edit]

If the edge length of a regular dodecahedron is , the radius of a circumscribed sphere (one that touches the regular dodecahedron at all vertices) is

(sequence A179296 in the OEIS)

and the radius of an inscribed sphere (tangent to each of the regular dodecahedron’s faces) is

while the midradius, which touches the middle of each edge, is

These quantities may also be expressed as

where ϕ is the golden ratio.

Note that, given a regular dodecahedron of edge length one, r_u is the radius of a circumscribing sphere about a cube of edge length ϕ, and r_i is the apothem of a regular pentagon of edge length ϕ.

Surface area and volume[edit]

The surface area A and the volume V of a regular dodecahedron of edge length a are:

Additionally, the surface area and volume of a regular dodecahedron are related to the golden ratio. A dodecahedron with an edge length of one unit has the properties:^[3]

Two-dimensional symmetry projections[edit]

The regular dodecahedron has two high orthogonal projections, centered, on vertices and pentagonal faces, correspond to the A₂ and H₂ Coxeter planes. The edge-center projection has two orthogonal lines of reflection.

Orthogonal projections

Centered by	Vertex	Face	Edge
Image
Projective symmetry	[[3]] = [6]	[[5]] = [10]	[2]

In perspective projection, viewed on top of a pentagonal face, the regular dodecahedron can be seen as a linear-edged Schlegel diagram, or stereographic projection as a spherical polyhedron. These projections are also used in showing the four-dimensional 120-cell, a regular 4-dimensional polytope, constructed from 120 dodecahedra, projecting it down to 3-dimensions.

Projection	Orthogonal projection	Perspective projection
Schlegel diagram	Stereographic projection
Regular dodecahedron
Dodecaplex (120-cell)

Spherical tiling[edit]

The regular dodecahedron can also be represented as a spherical tiling.

Orthographic projection	Stereographic projection

Cartesian coordinates[edit]

The following Cartesian coordinates define the 20 vertices of a regular dodecahedron centered at the origin and suitably scaled and oriented:^[4]

(±1, ±1, ±1)

(0, ±ϕ, ±1/ϕ)

(±1/ϕ, 0, ±ϕ)

(±ϕ, ±1/ϕ, 0)

where ϕ = 1 + √5/2 is the golden ratio (also written τ) ≈ 1.618. The edge length is 2/ϕ = √5 − 1. The circumradius is √3.

Facet-defining equations[edit]

Similar to the symmetry of the vertex coordinates, the equations of the twelve facets of the regular dodecahedron also display symmetry in their coefficients:

x ± ϕy = ±ϕ²

y ± ϕz = ±ϕ²

z ± ϕx = ±ϕ²

Properties[edit]

• The dihedral angle of a regular dodecahedron is 2 arctan(ϕ) or approximately 116.565° (where again ϕ = 1 + √5/2, the golden ratio). OEIS: A137218 Note that the tangent of the dihedral angle is exactly −2.
• If the original regular dodecahedron has edge length 1, its dual icosahedron has edge length ϕ.
• If the five Platonic solids are built with same volume, the regular dodecahedron has the shortest edges.
• It has 43,380 nets.
• The map-coloring number of a regular dodecahedron’s faces is 4.
• The distance between the vertices on the same face not connected by an edge is ϕ times the edge length.
• If two edges share a common vertex, then the midpoints of those edges form a 36-72-72 golden triangle with the body center.

As a configuration[edit]

This configuration matrix represents the dodecahedron. The rows and columns correspond to vertices, edges, and faces. The diagonal numbers say how many of each element occur in the whole dodecahedron. The nondiagonal numbers say how many of the column’s element occur in or at the row’s element.^[5][6]

Here is the configuration expanded with k-face elements and k-figures. The diagonal element counts are the ratio of the full Coxeter group H₃, order 120, divided by the order of the subgroup with mirror removal.

H3		k-face	fk	f0	f1	f2	k-fig	Notes
A2		( )	f0	20	3	3	{3}	H3/A2 = 120/6 = 20
A1A1		{ }	f1	2	30	2	{ }	H3/A1A1 = 120/4 = 30
H2		{5}	f2	5	5	12	( )	H3/H2 = 120/10 = 12

Geometric relations[edit]

The regular dodecahedron is the third in an infinite set of truncated trapezohedra which can be constructed by truncating the two axial vertices of a pentagonal trapezohedron.

The stellations of the regular dodecahedron make up three of the four Kepler–Poinsot polyhedra.

A rectified regular dodecahedron forms an icosidodecahedron.

The regular dodecahedron has icosahedral symmetry I_h, Coxeter group [5,3], order 120, with an abstract group structure of A₅ × Z₂.

Relation to the regular icosahedron[edit]

The dodecahedron and icosahedron are dual polyhedra. A regular dodecahedron has 12 faces and 20 vertices, whereas a regular icosahedron has 20 faces and 12 vertices. Both have 30 edges.

When a regular dodecahedron is inscribed in a sphere, it occupies more of the sphere’s volume (66.49%) than an icosahedron inscribed in the same sphere (60.55%).

A regular dodecahedron with edge length 1 has more than three and a half times the volume of an icosahedron with the same length edges (7.663… compared with 2.181…), which ratio is approximately 3.51246117975, or in exact terms: 3/5(3ϕ + 1) or (1.8ϕ + 0.6).

Relation to the nested cube[edit]

A cube can be embedded within a regular dodecahedron, affixed to eight of its equidistant vertices, in five different positions.^[7] In fact, five cubes may overlap and interlock inside the regular dodecahedron to result in the compound of five cubes.

The ratio of the edge of a regular dodecahedron to the edge of a cube embedded inside such a regular dodecahedron is 1 : ϕ, or (ϕ − 1) : 1.

The ratio of a regular dodecahedron’s volume to the volume of a cube embedded inside such a regular dodecahedron is 1 : 2/2 + ϕ, or 1 + ϕ/2 : 1, or (5 + √5) : 4.

For example, an embedded cube with a volume of 64 (and edge length of 4), will nest within a regular dodecahedron of volume 64 + 32ϕ (and edge length of 4ϕ − 4).

Thus, the difference in volume between the encompassing regular dodecahedron and the enclosed cube is always one half the volume of the cube times ϕ.

From these ratios are derived simple formulas for the volume of a regular dodecahedron with edge length a in terms of the golden mean:

V = (aϕ)³ · 1/4(5 + √5)

V = 1/4(14ϕ + 8)a³

Relation to the regular tetrahedron[edit]

As two opposing tetrahedra can be inscribed in a cube, and five cubes can be inscribed in a dodecahedron, ten tetrahedra in five cubes can be inscribed in a dodecahedron: two opposing sets of five, with each set covering all 20 vertices and each vertex in two tetrahedra (one from each set, but not the opposing pair).

Just as a tetrahedron can be inscribed in a cube, so a cube can be inscribed in a dodecahedron. By reciprocation, this leads to an octahedron circumscribed about an icosahedron. In fact, each of the twelve vertices of the icosahedron divides an edge of the octahedron according to the “golden section”. Given the icosahedron, the circumscribed octahedron can be chosen in five ways, giving a compound of five octahedra, which comes under our definition of stellated icosahedron. (The reciprocal compound, of five cubes whose vertices belong to a dodecahedron, is a stellated triacontahedron.) Another stellated icosahedron can at once be deduced, by stellating each octahedron into a stella octangula, thus forming a compound of ten tetrahedra. Further, we can choose one tetrahedron from each stella octangula, so as to derive a compound of five tetrahedra, which still has all the rotation symmetry of the icosahedron (i.e. the icosahedral group), although it has lost the reflections. By reflecting this figure in any plane of symmetry of the icosahedron, we obtain the complementary set of five tetrahedra. These two sets of five tetrahedra are enantiomorphous, i.e. not directly congruent, but related like a pair of shoes. [Such] a figure which possesses no plane of symmetry (so that it is enantiomorphous to its mirror-image) is said to be chiral.^[8]

Relation to the golden rectangle[edit]

Golden rectangles of ratio (ϕ + 1) : 1 and ϕ : 1 also fit perfectly within a regular dodecahedron.^[9] In proportion to this golden rectangle, an enclosed cube’s edge is ϕ, when the long length of the rectangle is ϕ + 1 (or ϕ²) and the short length is 1 (the edge shared with the regular dodecahedron).

In addition, the center of each face of the regular dodecahedron form three intersecting golden rectangles.^[10]

Relation to the 6-cube and rhombic triacontahedron[edit]

It can be projected to 3D from the 6-dimensional 6-demicube using the same basis vectors that form the hull of the rhombic triacontahedron from the 6-cube. Shown here including the inner 12 vertices, which are not connected by the outer hull edges of 6D norm length √2, form a regular icosahedron.

The 3D projection basis vectors [u,v,w] used are:

u = (1, ϕ, 0, −1, ϕ, 0)

v = (ϕ, 0, 1, ϕ, 0, −1)

w = (0, 1, ϕ, 0, −1, ϕ)

History and uses[edit]

Regular dodecahedral objects have found some practical applications, and have also played a role in the visual arts and in philosophy.

Iamblichus states that Hippasus, a Pythagorean, perished in the sea, because he boasted that he first divulged “the sphere with the twelve pentagons.”^[11] In Theaetetus, a dialogue of Plato, Plato hypothesized that the classical elements were made of the five uniform regular solids; these later became known as the platonic solids. Of the fifth Platonic solid, the dodecahedron, Plato obscurely remarked, “…the god used [it] for arranging the constellations on the whole heaven”. Timaeus (c. 360 BC), as a personage of Plato’s dialogue, associates the other four platonic solids with the four classical elements, adding that there is a fifth solid pattern which, though commonly associated with the regular dodecahedron, is never directly mentioned as such; “this God used in the delineation of the universe.”^[12] Aristotle also postulated that the heavens were made of a fifth element, which he called aithêr (aether in Latin, ether in American English).

Theaetetus gave a mathematical description of all five and may have been responsible for the first known proof that no other convex regular polyhedra exist.
Euclid completely mathematically described the Platonic solids in the Elements, the last book (Book XIII) of which is devoted to their properties. Propositions 13–17 in Book XIII describe the construction of the tetrahedron, octahedron, cube, icosahedron, and dodecahedron in that order. For each solid Euclid finds the ratio of the diameter of the circumscribed sphere to the edge length. In Proposition 18 he argues that there are no further convex regular polyhedra.

Regular dodecahedra have been used as dice and probably also as divinatory devices. During the Hellenistic era, small, hollow bronze Roman dodecahedra were made and have been found in various Roman ruins in Europe. Their purpose is not certain.

In 20th-century art, dodecahedra appear in the work of M. C. Escher, such as his lithographs Reptiles (1943) and Gravitation (1952). In Salvador Dalí’s painting The Sacrament of the Last Supper (1955), the room is a hollow regular dodecahedron. Gerard Caris based his entire artistic oeuvre on the regular dodecahedron and the pentagon, which is presented as a new art movement coined as Pentagonism.

In modern role-playing games, the regular dodecahedron is often used as a twelve-sided die, one of the more common polyhedral dice.

Immersive Media Company, a former Canadian digital imaging company, made the Dodeca 2360 camera, the world’s first 360° full-motion camera which captures high-resolution video from every direction simultaneously at more than 100 million pixels per second or 30 frames per second.^[promotion?] It is based on regular dodecahedron.^{[citation needed]}

The Megaminx twisty puzzle, alongside its larger and smaller order analogues, is in the shape of a regular dodecahedron.

In the children’s novel The Phantom Tollbooth, the regular dodecahedron appears as a character in the land of Mathematics. Each of his faces wears a different expression – e.g. happy, angry, sad – which he swivels to the front as required to match his mood.

In nature and supramolecules[edit]

The fossil coccolithophore Braarudosphaera bigelowii (see figure), a unicellular coastal phytoplanktonic alga, has a calcium carbonate shell with a regular dodecahedral structure about 10 micrometers across.^[13]

Some quasicrystals and cages have dodecahedral shape (see figure). Some regular crystals such as garnet and diamond are also said to exhibit “dodecahedral” habit, but this statement actually refers to the rhombic dodecahedron shape.^{[14] [1]}

Shape of the universe[edit]

Various models have been proposed for the global geometry of the universe. In addition to the primitive geometries, these proposals include the Poincaré dodecahedral space, a positively curved space consisting of a regular dodecahedron whose opposite faces correspond (with a small twist). This was proposed by Jean-Pierre Luminet and colleagues in 2003,^[15][16] and an optimal orientation on the sky for the model was estimated in 2008.^[17]

In Bertrand Russell’s 1954 short story “The Mathematician’s Nightmare: The Vision of Professor Squarepunt,” the number 5 said: “I am the number of fingers on a hand. I make pentagons and pentagrams. And but for me dodecahedra could not exist; and, as everyone knows, the universe is a dodecahedron. So, but for me, there could be no universe.”

Space filling with cube and bilunabirotunda[edit]

Regular dodecahedra fill space with cubes and bilunabirotundas (Johnson solid 91), in the ratio of 1 to 1 to 3.^[18][19] The dodecahedra alone make a lattice of edge-to-edge pyritohedra. The bilunabirotundas fill the rhombic gaps. Each cube meets six bilunabirotundas in three orientations.

Related polyhedra and tilings[edit]

The regular dodecahedron is topologically related to a series of tilings by vertex figure n³.

*n32 symmetry mutation of regular tilings: {n,3} v t e
Spherical	Euclidean	Compact hyperb.	Paraco.	Noncompact hyperbolic
{2,3}	{3,3}	{4,3}	{5,3}	{6,3}	{7,3}	{8,3}	{∞,3}	{12i,3}	{9i,3}	{6i,3}	{3i,3}

The regular dodecahedron can be transformed by a truncation sequence into its dual, the icosahedron:

Family of uniform icosahedral polyhedra
Symmetry: [5,3], (*532)	[5,3]+, (532)
{5,3}	t{5,3}	r{5,3}	t{3,5}	{3,5}	rr{5,3}	tr{5,3}	sr{5,3}
Duals to uniform polyhedra
V5.5.5	V3.10.10	V3.5.3.5	V5.6.6	V3.3.3.3.3	V3.4.5.4	V4.6.10	V3.3.3.3.5

Uniform octahedral polyhedra
Symmetry: [4,3], (*432)	[4,3]+ (432)	[1+,4,3] = [3,3] (*332)	[3+,4] (3*2)
{4,3}	t{4,3}	r{4,3} r{31,1}	t{3,4} t{31,1}	{3,4} {31,1}	rr{4,3} s2{3,4}	tr{4,3}	sr{4,3}	h{4,3} {3,3}	h2{4,3} t{3,3}	s{3,4} s{31,1}
		=	=	=				= or	= or	=
Duals to uniform polyhedra
V43	V3.82	V(3.4)2	V4.62	V34	V3.43	V4.6.8	V34.4	V33	V3.62	V35

The regular dodecahedron is a member of a sequence of otherwise non-uniform polyhedra and tilings, composed of pentagons with face configurations (V3.3.3.3.n). (For n > 6, the sequence consists of tilings of the hyperbolic plane.) These face-transitive figures have (n32) rotational symmetry.

n32 symmetry mutations of snub tilings: 3.3.3.3.n v t e
Symmetry n32	Spherical	Euclidean	Compact hyperbolic	Paracomp.
232	332	432	532	632	732	832	∞32
Snub figures
Config.	3.3.3.3.2	3.3.3.3.3	3.3.3.3.4	3.3.3.3.5	3.3.3.3.6	3.3.3.3.7	3.3.3.3.8	3.3.3.3.∞
Gyro figures
Config.	V3.3.3.3.2	V3.3.3.3.3	V3.3.3.3.4	V3.3.3.3.5	V3.3.3.3.6	V3.3.3.3.7	V3.3.3.3.8	V3.3.3.3.∞

Vertex arrangement[edit]

The regular dodecahedron shares its vertex arrangement with four nonconvex uniform polyhedra and three uniform polyhedron compounds.

Five cubes fit within, with their edges as diagonals of the regular dodecahedron’s faces, and together these make up the regular polyhedral compound of five cubes. Since two tetrahedra can fit on alternate cube vertices, five and ten tetrahedra can also fit in a regular dodecahedron.

Stellations[edit]

The 3 stellations of the regular dodecahedron are all regular (nonconvex) polyhedra: (Kepler–Poinsot polyhedra)

	0	1	2	3
Stellation	Regular dodecahedron	Small stellated dodecahedron	Great dodecahedron	Great stellated dodecahedron
Facet diagram

Dodecahedral graph[edit]

Regular dodecahedron graph
A Hamiltonian cycle in a dodecahedron.
Vertices	20
Edges	30
Radius	5
Diameter	5
Girth	5
Automorphisms	120 (A5 × Z2)[20]
Chromatic number	3
Properties	Hamiltonian, regular, symmetric, distance-regular, distance-transitive, 3-vertex-connected, planar graph
Table of graphs and parameters

The skeleton of the dodecahedron (the vertices and edges) form a graph. It is one of 5 Platonic graphs, each a skeleton of its Platonic solid.

This graph can also be constructed as the generalized Petersen graph G(10,2). The high degree of symmetry of the polygon is replicated in the properties of this graph, which is distance-transitive, distance-regular, and symmetric. The automorphism group has order 120. The vertices can be colored with 3 colors, as can the edges, and the diameter is 5.^[21]

The dodecahedral graph is Hamiltonian – there is a cycle containing all the vertices. Indeed, this name derives from a mathematical game invented in 1857 by William Rowan Hamilton, the icosian game. The game’s object was to find a Hamiltonian cycle along the edges of a dodecahedron.

Orthogonal projection

See also[edit]

• 120-cell, a regular polychoron (4D polytope whose surface consists of 120 dodecahedral cells)
• Braarudosphaera bigelowii − A dodecahedron shaped coccolithophore (a unicellular phytoplankton algae).
• Dodecahedrane (molecule)
• Pentakis dodecahedron
• Snub dodecahedron
• Truncated dodecahedron

References[edit]

External links[edit]

• Weisstein, Eric W. “Regular Dodecahedron”. MathWorld.
• Klitzing, Richard. “3D convex uniform polyhedra o3o5x – doe”.
• Editable printable net of a dodecahedron with interactive 3D view
• The Uniform Polyhedra
• Origami Polyhedra – Models made with Modular Origami
• Dodecahedron – 3-d model that works in your browser
• Virtual Reality Polyhedra The Encyclopedia of Polyhedra
  • VRML#Regular dodecahedron
• K.J.M. MacLean, A Geometric Analysis of the Five Platonic Solids and Other Semi-Regular Polyhedra
• Dodecahedron 3D Visualization
• Stella: Polyhedron Navigator: Software used to create some of the images on this page.
• How to make a dodecahedron from a Styrofoam cube
• The Greek, Indian, and Chinese Elements – Seven Element Theory

v t e Fundamental convex regular and uniform polytopes in dimensions 2–10
Family	An	Bn	I2(p) / Dn	E6 / E7 / E8 / F4 / G2	Hn
Regular polygon	Triangle	Square	p-gon	Hexagon	Pentagon
Uniform polyhedron	Tetrahedron	Octahedron • Cube	Demicube		Dodecahedron • Icosahedron
Uniform polychoron	Pentachoron	16-cell • Tesseract	Demitesseract	24-cell	120-cell • 600-cell
Uniform 5-polytope	5-simplex	5-orthoplex • 5-cube	5-demicube
Uniform 6-polytope	6-simplex	6-orthoplex • 6-cube	6-demicube	122 • 221
Uniform 7-polytope	7-simplex	7-orthoplex • 7-cube	7-demicube	132 • 231 • 321
Uniform 8-polytope	8-simplex	8-orthoplex • 8-cube	8-demicube	142 • 241 • 421
Uniform 9-polytope	9-simplex	9-orthoplex • 9-cube	9-demicube
Uniform 10-polytope	10-simplex	10-orthoplex • 10-cube	10-demicube
Uniform n-polytope	n-simplex	n-orthoplex • n-cube	n-demicube	1k2 • 2k1 • k21	n-pentagonal polytope
Topics: Polytope families • Regular polytope • List of regular polytopes and compounds

Общая площадь поверхности додекаэдра Калькулятор

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Общая площадь поверхности додекаэдра Решение

ШАГ 0: Сводка предварительного расчета

ШАГ 1. Преобразование входов в базовый блок

Длина ребра додекаэдра: 10 метр –> 10 метр Конверсия не требуется

ШАГ 2: Оцените формулу

ШАГ 3: Преобразуйте результат в единицу вывода

2064.57288070676 Квадратный метр –> Конверсия не требуется

12 Общая площадь поверхности додекаэдра Калькуляторы

8 Площадь додекаэдра Калькуляторы

Общая площадь поверхности додекаэдра формула

Общая площадь поверхности додекаэдра = 3*sqrt(25+(10*sqrt(5)))*Длина ребра додекаэдра^2

TSA = 3*sqrt(25+(10*sqrt(5)))*l_e^2

Что такое додекаэдр?

Додекаэдр представляет собой симметричную и замкнутую трехмерную форму с 12 одинаковыми пятиугольными гранями. Это платоново тело, имеющее 12 граней, 20 вершин и 30 ребер. В каждой вершине встречаются три пятиугольные грани, а в каждом ребре встречаются две пятиугольные грани. Из всех пяти платоновых тел с одинаковой длиной ребра додекаэдр будет иметь наибольшее значение объема и площади поверхности.

Что такое Платоновые тела?

В трехмерном пространстве Платоново тело представляет собой правильный выпуклый многогранник. Он строится из конгруэнтных (одинаковых по форме и размеру), правильных (все углы равны и все стороны равны) многоугольных граней с одинаковым числом граней, сходящихся в каждой вершине. Пять тел, отвечающих этому критерию, — это тетраэдр {3,3}, куб {4,3}, октаэдр {3,4}, додекаэдр {5,3}, икосаэдр {3,5}; где в {p, q} p представляет количество ребер на грани, а q представляет количество ребер, встречающихся в вершине; {p, q} — символ Шлефли.