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Dodecahedral Number
A dodecahedral number is a figurate number that represents a dodecahedron. The ''n''th dodecahedral number is given by the formula = The first such numbers are 0, 1, 20, 84, 220, 455, 816, 1330, 2024, 2925, 4060, 5456, 7140, 9139, 11480, … . History The first study of dodecahedral numbers appears to have been by René Descartes, around 1630, in his ''De solidorum elementis''. Prior to Descartes, figurate numbers had been studied by the ancient Greeks and by Johann Faulhaber, but only for polygonal numbers, pyramidal numbers, and cubes. Descartes introduced the study of figurate numbers based on the Platonic solids and some semiregular polyhedra; his work included the dodecahedral numbers. However, ''De solidorum elementis'' was lost, and not rediscovered until 1860. In the meantime, dodecahedral numbers had been studied again by other mathematicians, including Friedrich Wilhelm Marpurg in 1774, Georg Simon Klügel Georg Simon Klügel (August 19, 1739 – August 4, 1812) wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Figurate Number
The term figurate number is used by different writers for members of different sets of numbers, generalizing from triangular numbers to different shapes (polygonal numbers) and different dimensions (polyhedral numbers). The term can mean * polygonal number * a number represented as a discrete -dimensional regular geometry, geometric pattern of -dimensional Ball (mathematics), balls such as a polygonal number (for ) or a polyhedral number (for ). * a member of the subset of the sets above containing only triangular numbers, pyramidal numbers, and their analogs in other dimensions. Terminology Some kinds of figurate number were discussed in the 16th and 17th centuries under the name "figural number". In historical works about Greek mathematics the preferred term used to be ''figured number''. In a use going back to Jacob Bernoulli's Ars Conjectandi, the term ''figurate number'' is used for triangular numbers made up of successive integers, tetrahedral numbers made up of successi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dodecahedron
In geometry, a dodecahedron (Greek , from ''dōdeka'' "twelve" + ''hédra'' "base", "seat" or "face") or duodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagons as faces, which is a Platonic solid. There are also three regular star dodecahedra, which are constructed as stellations of the convex form. All of these have icosahedral symmetry, order 120. Some dodecahedra have the same combinatorial structure as the regular dodecahedron (in terms of the graph formed by its vertices and edges), but their pentagonal faces are not regular: The pyritohedron, a common crystal form in pyrite, has pyritohedral symmetry, while the tetartoid has tetrahedral symmetry. The rhombic dodecahedron can be seen as a limiting case of the pyritohedron, and it has octahedral symmetry. The elongated dodecahedron and trapezo-rhombic dodecahedron variations, along with the rhombic dodecahedra, are space-filling. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
René Descartes
René Descartes ( or ; ; Latinized: Renatus Cartesius; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and science. Mathematics was central to his method of inquiry, and he connected the previously separate fields of geometry and algebra into analytic geometry. Descartes spent much of his working life in the Dutch Republic, initially serving the Dutch States Army, later becoming a central intellectual of the Dutch Golden Age. Although he served a Protestant state and was later counted as a deist by critics, Descartes considered himself a devout Catholic. Many elements of Descartes' philosophy have precedents in late Aristotelianism, the revived Stoicism of the 16th century, or in earlier philosophers like Augustine. In his natural philosophy, he differed from the schools on two major points: first, he rejected the splitting of corporeal substance into mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johann Faulhaber
Johann Faulhaber (5 May 1580 – 10 September 1635) was a German mathematician. Born in Ulm, Faulhaber was a trained weaver who later took the role of a surveyor of the city of Ulm. He collaborated with Johannes Kepler and Ludolph van Ceulen. Besides his work on the fortifications of cities (notably Basel and Frankfurt), Faulhaber built water wheels in his home town and geometrical instruments for the military. Faulhaber made the first publication of Henry Briggs's Logarithm in Germany. He is also credited with the first printed solution of equal temperament.Date,name,ratio,cents: from equal temperament monochord tables p55-p78; J. Murray Barbour ''Tuning and Temperament'', Michigan State University Press 1951 He died in Ulm. Faulhaber's major contribution was in calculating the sums of powers of integers. Jacob Bernoulli makes references to Faulhaber in his ''Ars Conjectandi''. Works * See also * Faulhaber's formula In mathematics, Faulhaber's formula, named after the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polygonal Number
In mathematics, a polygonal number is a number represented as dots or pebbles arranged in the shape of a regular polygon. The dots are thought of as alphas (units). These are one type of 2-dimensional figurate numbers. Definition and examples The number 10 for example, can be arranged as a triangle (see triangular number): : But 10 cannot be arranged as a square (geometry), square. The number 9, on the other hand, can be (see square number): : Some numbers, like 36, can be arranged both as a square and as a triangle (see square triangular number): : By convention, 1 is the first polygonal number for any number of sides. The rule for enlarging the polygon to the next size is to extend two adjacent arms by one point and to then add the required extra sides between those points. In the following diagrams, each extra layer is shown as in red. Triangular numbers : Square numbers : Polygons with higher numbers of sides, such as pentagons and hexagons, can also be constructe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyramidal Number
A pyramidal number is a figurate number that represents a pyramid with a polygonal base and a given number of triangular sides. A pyramidal number is the number of points in a pyramid where each layer of the pyramid is an -sided polygon of points. The term often refers to square pyramidal numbers, which have a square base with four sides, but it can also refer to pyramids with three or more sides. The numbers of points in the base (and in parallel layers to the base) are given by polygonal numbers of the given number of sides, while the numbers of points in each triangular side is given by a triangular number. It is possible to extend the pyramidal numbers to higher dimensions. Formula The formula for the th -gonal pyramidal number is :P_n^r= \frac, where , . This formula can be factored: :P_n^r=\frac=\left(\frac\right)\left(\frac\right)=T_n \cdot \frac, where is the th triangular number. Sequences The first few triangular pyramidal numbers (equivalently, tetrahedral numb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cube (algebra)
In arithmetic and algebra, the cube of a number is its third power, that is, the result of multiplying three instances of together. The cube of a number or any other mathematical expression is denoted by a superscript 3, for example or . The cube is also the number multiplied by its square: :. The ''cube function'' is the function (often denoted ) that maps a number to its cube. It is an odd function, as :. The volume of a geometric cube is the cube of its side length, giving rise to the name. The inverse operation that consists of finding a number whose cube is is called extracting the cube root of . It determines the side of the cube of a given volume. It is also raised to the one-third power. The graph of the cube function is known as the cubic parabola. Because the cube function is an odd function, this curve has a center of symmetry at the origin, but no axis of symmetry. In integers A cube number, or a perfect cube, or sometimes just a cube, is a number wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platonic Solid
In geometry, a Platonic solid is a convex, regular polyhedron in three-dimensional Euclidean space. Being a regular polyhedron means that the faces are congruent (identical in shape and size) regular polygons (all angles congruent and all edges congruent), and the same number of faces meet at each vertex. There are only five such polyhedra: Geometers have studied the Platonic solids for thousands of years. They are named for the ancient Greek philosopher Plato who hypothesized in one of his dialogues, the ''Timaeus'', that the classical elements were made of these regular solids. History The Platonic solids have been known since antiquity. It has been suggested that certain carved stone balls created by the late Neolithic people of Scotland represent these shapes; however, these balls have rounded knobs rather than being polyhedral, the numbers of knobs frequently differed from the numbers of vertices of the Platonic solids, there is no ball whose knobs match the 20 vertic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiregular Polyhedron
In geometry, the term semiregular polyhedron (or semiregular polytope) is used variously by different authors. Definitions In its original definition, it is a polyhedron with regular polygonal faces, and a symmetry group which is transitive on its vertices; today, this is more commonly referred to as a uniform polyhedron (this follows from Thorold Gosset's 1900 definition of the more general semiregular polytope). These polyhedra include: *The thirteen Archimedean solids. ** The elongated square gyrobicupola, also called a pseudo-rhombicuboctahedron, a Johnson solid, has identical vertex figures 3.4.4.4, but is not vertex-transitive including a twist has been argued for inclusion as a 14th Archimedean solid by Branko Grünbaum. *An infinite series of convex prisms. *An infinite series of convex antiprisms (their semiregular nature was first observed by Kepler). These semiregular solids can be fully specified by a vertex configuration: a listing of the faces by number of sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedrich Wilhelm Marpurg
Friedrich Wilhelm Marpurg (21 November 1718 – 22 May 1795) was a German music critic, music theorist and composer. He was friendly and active with many figures of the Enlightenment of the 18th century. Life Little is known of Marpurg's early life. According to various sources, he studied "philosophy" and music. It is clear that he enjoyed a strong education and was friendly with various leading figures of the Enlightenment, including Winckelmann and Lessing. In 1746, he travelled to Paris as the secretary for a General named either Rothenberg or Bodenberg. There, he became acquainted with intellectuals including the writer and philosopher Voltaire, the mathematician d'Alembert and the composer Jean-Philippe Rameau. After 1746, he returned to Berlin where he was more or less independent. Marpurg's offer to write exclusively for Breitkopf & Härtel was declined by the firm in 1757. In 1760, he received an appointment to the Royal Prussian Lotteries, whose director he became ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Georg Simon Klügel
Georg Simon Klügel (August 19, 1739 – August 4, 1812) was a German mathematician and physicist. He was born in Hamburg, and in 1760 went to the University of Göttingen where he initially studied theology before switching to mathematics. Georg Christoph Lichtenberg was a fellow student. His doctoral thesis ''Conatuum praecipuorum theoriam parallelarum demonstrandi recensio'', published in 1763 with Abraham Gotthelf Kästner as doctoral advisor, was a study of 30 attempted proofs of the parallel postulate. It was influential at the time and much cited. Klügel edited the ''Hannöversche Magazin'' for 2 years from 1766, before becoming professor of mathematics at the University of Helmstedt. In 1788 he succeeded Wenzeslaus Johann Gustav Karsten to the chair of mathematics and physics at the University of Halle. He died in Halle in 1812. He remained in correspondence with Lichtenberg throughout his career. Klügel made an exceptional contribution to trigonometry, unifying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sir Frederick Pollock, 1st Baronet
Sir Jonathan Frederick Pollock, 1st Baronet, PC (23 September 1783 – 28 August 1870) was a British lawyer and Tory politician. Background and education Pollock was the son of saddler David Pollock, of Charing Cross, London, and the elder brother of Field Marshal Sir George Pollock, 1st Baronet. An elder brother, Sir David Pollock, was a judge in India. The Pollock family were a branch of that family of Balgray, Dumfriesshire; David Pollock's father was a burgess of Berwick-upon-Tweed, and his grandfather a yeoman of Durham. His business as a saddler was given the official custom of the royal family. Sir John Pollock, 4th Baronet, great-great-grandson of David Pollock, stated in Time's Chariot (1950) that David was, 'perhaps without knowing it', Pollock of Balgray, the senior line of the family (Pollock of Pollock or Pollock of that ilk) having died out. Pollock was educated at St Paul's School and Trinity College, Cambridge. He was Senior Wrangler at Cambridge University. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
