The cube can be represented in many ways, such as the cubical graph, which can be constructed by using the Cartesian product of graphs. The cube is the three-dimensional hypercube, a family of polytopes also including the two-dimensional square and four-dimensional tesseract. A cube with unit side length is the canonical unit of volume in three-dimensional space, relative to which other solid objects are measured. Other related figures involve the construction of polyhedra, space-filling and honeycombs, and polycubes, as well as cubes in compounds, spherical, and topological space.
The cube was discovered in antiquity, and associated with the nature of earth by Plato, for whom the Platonic solids are named. It can be derived differently to create more polyhedra, and it has applications to construct a new polyhedron by attaching others. Other applications are found in toys and games, arts, optical illusions, architectural buildings, natural science, and technology.
Properties
3D model of a cube
A cuboid is a polyhedron that consists of six quadrilateral faces. When all of its interior angle (the angle formed inside) are right angles, 90°, the faces are transformed into rectangles, which is known as rectangular cuboid. A cube becomes a special case ofa rectangular cuboidwhen all of the edges are equal in length.[1] Like a rectangular cuboid, every face of a cube has four vertices, each of which connects with three lines of the same length. These edges form square faces, so the dihedral angle of a cube—the angle between every two adjacent squares—is the interior angle of a square as well. Hence, the cube has six faces, twelve edges, and eight vertices.[2] As for all convex polyhedra, the cube has Euler characteristic of 2, according to the formula ; the three letters denote respectively the number of vertices, edges, and faces.[3]
Every three square faces surrounding a vertex are orthogonal to each other, meaning the planes are perpendicular, forming a right angle between two adjacent squares. Hence, the cube is classified as an orthogonal polyhedron.[4] Other special cases for a cube are a parallelepiped—a polyhedron with six parallelograms faces—because its pairs of opposite faces are congruent,[5] a rhombohedron—as a special case of a parallelepiped with six rhombi faces—because the interior angle of all of the faces is right,[6] and a trigonal trapezohedron—a polyhedron with congruent quadrilateral faces—since its square faces are the special cases of rhombi.[7]
Measurement and other metric properties
A face diagonal in red and space diagonal in blue
Given a cube with edge length , the face diagonal of the cube is the diagonal of a square , and the space diagonal of the cube is a line connecting two vertices that are not in the same face, formulated as . Both formulas can be determined by using the Pythagorean theorem. The surface area of a cube is six times the area of a square:[8] The volume of a cuboid is the product of its length, width, and height. Because all the edges of a cube are equal in length, the formula for the volume of a cube is the third power of its side length, leading to the use of the term cubic to mean raising any number to the third power:[9][8]
The cube has three types of closed geodesics, or paths on a cube's surface that are locally straight. In other words, they avoid the vertices, follow line segments across the faces that they cross, and form complementary angles on the two incident faces of each edge that they cross. One type lies in a plane parallel to any face of the cube, forming a square congruent to a face, four times the length of each edge. Another type lies in a plane perpendicular to the long diagonal, forming a regular hexagon; its length is times that of an edge. The third type is a non-planar hexagon.[15]
Insphere, midsphere, circumsphere
With edge length , the inscribed sphere of a cube is the sphere tangent to the faces of a cube at their centroids, with radius . The midsphere of a cube is the sphere tangent to the edges of a cube, with radius . The circumscribed sphere of a cube is the sphere tangent to the vertices of a cube, with radius .[16]
For a cube whose circumscribed sphere has radius , and for a given point in its three-dimensional space with distances from the cube's eight vertices, it is:[17]
Symmetry
The dual polyhedron of a cube is the regular octahedron. Both have octahedral symmetry.
The cube has octahedral symmetry of order 48. In other words, the cube has 48 isometries, each of which transforms the cube to itself. These transformations include nine reflection symmetries (where two halves cut by a plane are identical): three cut the cube at the midpoints of its edges, and six cut diagonally. The cube also has thirteen axes of rotational symmetry (whereby rotation around the axis results in an identical appearance): three axes pass through the centroids of the cube's opposite faces, six through the midpoints of the cube's opposite edges, and four through the cube's opposite vertices; these axes are respectively four-fold rotational symmetry (0°, 90°, 180°, and 270°), two-fold rotational symmetry (0° and 180°), and three-fold rotational symmetry (0°, 120°, and 240°).[18][19][20][21]
The dual polyhedron can be obtained from each of the polyhedra's vertices tangent to a plane by a process known as polar reciprocation.[22] One property of dual polyhedra is that the polyhedron and its dual share their three-dimensional symmetry point group. In this case, the dual polyhedron of a cube is the regular octahedron, and both of these polyhedra have the same octahedral symmetry.[23]
The cube is face-transitive, meaning its two squares are alike and can be mapped by rotation and reflection.[24] It is vertex-transitive, meaning all of its vertices are equivalent and can be mapped isometrically under its symmetry.[25] It is also edge-transitive, meaning the same kind of faces surround each of its vertices in the same or reverse order, and each pair of adjacent faces has the same dihedral angle. Therefore, the cube is a regular polyhedron.[26] Each vertex is surrounded by three squares, so the cube is by vertex configuration or in a Schläfli symbol.[27]
The Platonic solids are five polyhedra known since antiquity. The set is named for Plato who, in his dialogue Timaeus, attributed these solids to nature. One of them, the cube, represented the classical element of earth because of its stability.[48]Euclid's Elements defined the Platonic solids, including the cube, and showed how to find the ratio of the circumscribed sphere's diameter to the edge length.[49] Following Plato's use of the regular polyhedra as symbols of nature, Johannes Kepler in his Harmonices Mundi sketched each of the Platonic solids; he decorated the cube's side with a tree.[48] In his Mysterium Cosmographicum, Kepler also proposed that the ratios between sizes of the orbits of the planets are the ratios between the sizes of the inscribed and circumscribed spheres of the Platonic solids. That is, if the orbits are great circles on spheres, the sphere of Mercury is tangent to a regular octahedron, whose vertices lie on the sphere of Venus, which is in turn tangent to a regular icosahedron, within the sphere of Earth, within a regular dodecahedron, within the sphere of Mars, within a regular tetrahedron, within the sphere of Jupiter, within a cube, within the sphere of Saturn. In fact, the orbits are not circles but ellipses (as Kepler himself later showed), and these relations are only approximate.[50]
Construction
The eleven nets of a cube
An elementary way to construct a cube is using its net, an arrangement of edge-joined polygons, by connecting the free edges of those polygons. Eleven nets for the cube are possible.[51][52]
In analytic geometry, a cube may be constructed using the Cartesian coordinate systems. For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are .[53] Its interior consists of all points with for all . A cube's surface with center and edge length of is the locus of all points such that
The cube is a Hanner polytope, because it can be constructed by using the Cartesian product of three line segments. Its dual polyhedron, the regular octahedron, is constructed by the direct sum of three line segments.[54]
According to Steinitz's theorem, a graph can be represented as the vertex-edge graph of a polyhedron. Such a graph has two properties: planar (the edges of a graph are connected to every vertex without crossing other edges), and 3-connected (whenever a graph with more than three vertices, and two of the vertices are removed, the edges remain connected).[55][56] The skeleton of a cube, represented as the graph, is called the cubical graph, a Platonic graph. It has the same number of vertices and edges as the cube, twelve vertices and eight edges.[57] The cubical graph is also classified as a prism graph, resembling the skeleton of a cuboid.[58]
The cubical graph is a special case of hypercube graph or -cube—denoted as —because it can be constructed by using the Cartesian product of graphs: two graphs connecting the pair of vertices with an edge to form a new graph.[59] In the case of the cubical graph, it is the product of . In other words, the cubical graph is constructed by connecting each vertex of two squares with an edge. Notationally, the cubical graph is .[60] Like any hypercube graph, it has a cycle which visits every vertex exactly once,[61] and it is also an example of a unit distance graph.[62]
An object illuminated by parallel rays of light casts a shadow on a plane perpendicular to those rays, called an orthogonal projection. A polyhedron is considered equiprojective if, for some position of the light, its orthogonal projection is a regular polygon. The cube is equiprojective because, if the light is parallel to one of the four lines joining a vertex to the opposite vertex, its projection is a regular hexagon.[66]
As a configuration matrix
The cube can be represented as a configuration matrix, a matrix in which the rows and columns correspond to the elements of a polyhedron as the vertices, edges, and faces. The diagonal of a matrix denotes the number of each element that appears in a polyhedron, whereas the non-diagonal of a matrix denotes the number of the column's elements that occur in or at the row's element. The cube's eight vertices, twelve edges, and six faces are denoted by each element in a matrix's diagonal (8, 12, and 6). The first column of the middle row indicates that there are two vertices on each edge, denoted as 2; the middle column of the first row indicates that three edges meet at each vertex, denoted as 3. The following matrix is:[67]
Related figures
Truncation
The chamfered cube
Each of the cube's vertices can be truncated, and the resulting polyhedron is the Archimedean solid, the truncated cube.[68] When its edges are truncated, it is a rhombicuboctahedron.[69] Relatedly, the rhombicuboctahedron can also be constructed by separating the cube's faces and then spreading away, after which adding other triangular and square faces between them; this is known as the "expanded cube". The same figure can be derived in the same way from the cube's dual, the regular octahedron.[70]
In addition to truncation, the cube can be applied in many constructions of a polyhedron. Some of its types can be derived differently in the following:
When faceting a cube, meaning removing part of the polygonal faces without creating new vertices of a cube, the resulting polyhedron is the stellated octahedron.[73]
The cube is a non-composite polyhedron, meaning there is no plane intersecting its surface only along edges, by which it could be cut into two or more polyhedra.
The corner region of a cube can also be truncated by a plane (e.g., spanned by the three neighboring vertices), resulting in a trirectangular tetrahedron.[78]
The snub cube is an Archimedean solid that can be constructed by separating the cube's faces, and filling the gaps with twisted angle equilateral triangles, a process known as a snub.[79]
Three mutually perpendicular golden rectangles can be constructed from a pair of vertices located on the midpoints of the opposite edges on a cube's surface, drawing a segment line between those two, and dividing that segment line in a golden ratio from its midpoint. The corners of these rectangles are the vertices of a regular icosahedron with twenty equilateral triangles.[80]
The cube can be constructed with six square pyramids, tiling space by attaching their apices. In some cases, this produces the rhombic dodecahedron circumscribing a cube.[81][82]
The polycube is a polyhedron in which the faces of many cubes are attached. Analogously, it can be interpreted as the polyominoes in three-dimensional space.[83]
When four cubes are stacked vertically, and four others are attached to the second-from-top cube of the stack, the resulting polycube is the Dalí cross, named after Salvador Dalí. The Dalí cross can be folded in a fourth dimension to enclose a tesseract. It can also tile three-dimensional space.[84][85] Both cube and tesseract are known as three-dimensional and four-dimensional hypercubes, respectively.[86]
Space-filling and honeycombs
Hilbert's third problem asks whether every two equal-volume polyhedra can always be dissected into polyhedral pieces and reassembled into each other. If yes, then the volume of any polyhedron could be defined axiomatically as the volume of an equivalent cube into which it could be reassembled. Max Dehn solved this problem by inventing the Dehn invariant, answering that not all polyhedra can be reassembled into a cube.[87] It showed that two equal volume polyhedra should have the same Dehn invariant, except for the two tetrahedra whose Dehn invariants were different.[88]
The cube has a Dehn invariant of zero, meaning that cubes can achieve a honeycomb. It is also a space-filling tile in three-dimensional space in which the construction begins by attaching a polyhedron onto its faces without leaving a gap.[89] The cube is a plesiohedron, a special kind of space-filling polyhedron that can be defined as the Voronoi cell of a symmetric Delone set.[90] The plesiohedra include the parallelohedra, which can be translated without rotating to fill a space in which each face of any of its copies is attached to a like face of another copy. There are five kinds of parallelohedra, one of which is the parallelepiped.[91] Every three-dimensional parallelohedron is a zonohedron, a centrally symmetric polyhedron whose faces are centrally symmetric polygons.[92] In the case of the cube, it can be represented as a cell. Some honeycombs have cubes as the only cells; one example is the cubic honeycomb, the only regular honeycomb in Euclidean three-dimensional space, which has four cubes around each edge.[93][94]
The spherical cube represents the spherical polyhedron, which can be modeled by the arc of great circles, creating bounds as the edges of a spherical square.[97] Hence, the spherical cube consists of six spherical squares with 120° interior angles on each vertex. It has vector equilibrium, meaning that the distance from the centroid and each vertex is the same as the distance from that and each edge.[98][99] Its dual is the spherical octahedron.[97]
The topological object three-dimensional torus is a topological space defined to be homeomorphic to the Cartesian product of three circles. It can be represented as a three-dimensional model of the cube shape.[100]
↑ Sriraman, Bharath (2009). "Mathematics and literature (the sequel): imagination as a pathway to advanced mathematical ideas and philosophy". In Sriraman, Bharath; Freiman, Viktor; Lirette-Pitre, Nicole (eds.). Interdisciplinarity, Creativity, and Learning: Mathematics With Literature, Paradoxes, History, Technology, and Modeling. The Montana Mathematics Enthusiast: Monograph Series in Mathematics Education. Vol.7. Information Age Publishing, Inc. pp.41–54. ISBN9781607521013.
↑ Fuchs, Dmitry; Fuchs, Ekaterina (2007). "Closed Geodesics on Regular Polyhedra". Moscow Mathematical Journal. 7 (2): 265–279. doi:10.17323/1609-4514-2007-7-2-265-279 (inactive 1 July 2025).{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
↑ Coxeter (1973) Table I(i), pp. 292–293. See the columns labeled , , and , Coxeter's notation for the circumradius, midradius, and inradius, respectively, also noting that Coxeter uses as the edge length (see p. 2).
↑ Fowler, David (2010). "Mathematics in Science Fiction: Mathematics as Science Fiction". World Literature Today. 84 (3): 48–52. doi:10.1353/wlt.2010.0188. JSTOR27871086. S2CID115769478. Robert Heinlein's "And He Built a Crooked House," published in 1940, and Martin Gardner's "The No-Sided Professor," published in 1946, are among the first in science fiction to introduce readers to the Moebius band, the Klein bottle, and the hypercube (tesseract).
↑ March, Lionel (1996). "Renaissance mathematics and architectural proportion in Alberti's De re aedificatoria". Architectural Research Quarterly. 2 (1): 54–65. doi:10.1017/S135913550000110X. S2CID110346888.
↑ Chin, Daniel Jie Yuan Chin; Mohamed, Ahmad Sufril Azlan; Shariff, Khairul Anuar; Ishikawa, Kunio (23–25 November 2021). "GPU-Accelerated Enhanced Marching Cubes 33 for Fast 3D Reconstruction of Large Bone Defect CT Images". In Zaman, Halimah Badioze; Smeaton, Alan; Shih, Timothy; Velastin, Sergio; Terutoshi, Tada; Jørgensen, Bo Nørregaard; Aris, Hazleen Aris; Ibrahim, Nazrita Ibrahim (eds.). Advances in Visual Informatics. 7th International Visual Informatics Conference. Kajang, Malaysia. p.376.
↑ Greene, N (1986). "Environment mapping and other applications of world projections". IEEE Computer Graphics and Applications. 6 (11): 21–29. doi:10.1109/MCG.1986.276658. S2CID11301955.
↑ Jeon, Kyungsoon (2009). "Mathematics Hiding in the Nets for a CUBE". Teaching Children Mathematics. 15 (7): 394–399. doi:10.5951/TCM.15.7.0394. JSTOR41199313.
↑ Viana, Vera; Xavier, João Pedro; Aires, Ana Paula; Campos, Helena (2019). "Interactive Expansion of Achiral Polyhedra". In Cocchiarella, Luigi (ed.). ICGG 2018 - Proceedings of the 18th International Conference on Geometry and Graphics 40th Anniversary - Milan, Italy, August 3-7, 2018. Advances in Intelligent Systems and Computing. Vol.809. Springer. p.1123. doi:10.1007/978-3-319-95588-9. ISBN978-3-319-95587-2. See Fig. 6.
↑ Gruber, Peter M. (2007). "Chapter 16: Volume of Polytopes and Hilbert's Third Problem". Convex and Discrete Geometry. Grundlehren der mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences]. Vol.336. Springer, Berlin. pp.280–291. doi:10.1007/978-3-540-71133-9. ISBN978-3-540-71132-2. MR2335496.
↑ In higher dimensions, however, there exist parallelopes that are not zonotopes. See e.g. Shephard, G. C. (1974). "Space-filling zonotopes". Mathematika. 21 (2): 261–269. doi:10.1112/S0025579300008652. MR0365332.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.