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Reuleaux Polygon
In geometry, a Reuleaux polygon is a curve of constant width made up of circular arcs of constant radius. These shapes are named after their prototypical example, the Reuleaux triangle, which in turn, is named after 19th-century German engineer Franz Reuleaux. The Reuleaux triangle can be constructed from an equilateral triangle by connecting each two vertices by a circular arc centered on the third vertex, and Reuleaux polygons can be formed by a similar construction from any regular polygon with an odd number of sides, or from certain irregular polygons. Every curve of constant width can be accurately approximated by Reuleaux polygons. They have been applied in coinage shapes. Construction If P is a convex polygon with an odd number of sides, in which each vertex is equidistant to the two opposite vertices and closer to all other vertices, then replacing each side of P by an arc centered at its opposite vertex produces a Reuleaux polygon. As a special case, this construction i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convex Hull
In geometry, the convex hull or convex envelope or convex closure of a shape is the smallest convex set that contains it. The convex hull may be defined either as the intersection of all convex sets containing a given subset of a Euclidean space, or equivalently as the set of all convex combinations of points in the subset. For a bounded subset of the plane, the convex hull may be visualized as the shape enclosed by a rubber band stretched around the subset. Convex hulls of open sets are open, and convex hulls of compact sets are compact. Every compact convex set is the convex hull of its extreme points. The convex hull operator is an example of a closure operator, and every antimatroid can be represented by applying this closure operator to finite sets of points. The algorithmic problems of finding the convex hull of a finite set of points in the plane or other low-dimensional Euclidean spaces, and its dual problem of intersecting half-spaces, are fundamental problems of com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plus Magazine
''Plus Magazine'' is an online popular mathematics magazine run under the Millennium Mathematics Project at the University of Cambridge. ''Plus'' contains: * feature articles on all aspects of mathematics; * reviews of popular maths books and events; * a news section; * mathematical puzzles and games; * interviews with people in maths related careers; * ''Plus'' Podcast – Maths on the Move History ''Plus'' was initially named PASS Maths (Public Awareness and Schools Support for Maths) in 1997, when it was a project of the Interactive Courseware Research and Development Group, based jointly at the University of Cambridge and Keele University. ''Plus'' is now part of the Millennium Mathematics Project, a long term national initiative based in Cambridge and active across the UK and internationally. Authors of articles in ''Plus'' include Stephen Hawking and Marcus du Sautoy. ''Plus'' won the 2001 Webby for ''Best Science Site on the Web'', and has been described as "an e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geometriae Dedicata
''Geometriae Dedicata'' is a mathematical journal, founded in 1972, concentrating on geometry and its relationship to topology, group theory and the theory of dynamical systems. It was created on the initiative of Hans Freudenthal in Utrecht, the Netherlands.. It is published by Springer Netherlands. The Editors-in-Chief An editor-in-chief (EIC), also known as lead editor or chief editor, is a publication's editorial leader who has final responsibility for its operations and policies. The highest-ranking editor of a publication may also be titled editor, managing ... are John R. Parker and Jean-Marc Schlenker.Journal website References External links Springer site Mathematics journals Springer Science+Business Media academic journals {{math-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific Journal Of Mathematics
The Pacific Journal of Mathematics is a mathematics research journal supported by several universities and research institutes, and currently published on their behalf by Mathematical Sciences Publishers, a non-profit academic publishing organisation, and the University of California, Berkeley. It was founded in 1951 by František Wolf and Edwin F. Beckenbach and has been published continuously since, with five two-issue volumes per year and 12 issues per year. Full-text PDF versions of all journal articles are available on-line via the journal's website with a subscription. The journal is incorporated as a 501(c)(3) organization. References Mathematics journals Publications established in 1951 Mathematical Sciences Publishers academic journals {{math-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Pound
Sterling (abbreviation: stg; Other spelling styles, such as STG and Stg, are also seen. ISO code: GBP) is the currency of the United Kingdom and nine of its associated territories. The pound ( sign: £) is the main unit of sterling, and the word "pound" is also used to refer to the British currency generally, often qualified in international contexts as the British pound or the pound sterling. Sterling is the world's oldest currency that is still in use and that has been in continuous use since its inception. It is currently the fourth most-traded currency in the foreign exchange market, after the United States dollar, the euro, and the Japanese yen. Together with those three currencies and Renminbi, it forms the basket of currencies which calculate the value of IMF special drawing rights. As of mid-2021, sterling is also the fourth most-held reserve currency in global reserves. The Bank of England is the central bank for sterling, issuing its own banknotes, and regu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loonie
The loonie (french: huard), formally the Canadian one-dollar coin, is a gold-coloured Canadian coin that was introduced in 1987 and is produced by the Royal Canadian Mint at its facility in Winnipeg. The most prevalent versions of the coin show a common loon, a bird found throughout Canada, on the reverse and Queen Elizabeth II, the nation's head of state at the time of the coin's issue, on the obverse. Various commemorative and specimen-set editions of the coin with special designs replacing the loon on the reverse have been minted over the years. The coin's outline is an 11-sided Reuleaux polygon. Its diameter of 26.5 mm and its 11-sidedness matched that of the already-circulating Susan B. Anthony dollar in the United States, and its thickness of 1.95 mm was a close match to the latter's 2.0 mm. Its gold colour differed from the silver-coloured Anthony dollar; however, the succeeding Sacagawea and Presidential dollars matched the loonie's overall hue. Othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fifty Pence (British Coin)
The United Kingdom, British decimal fifty pence coin (often shortened to 50p in writing and speech) is a denomination of Coins of the United Kingdom, sterling coinage worth one half of a pound sterling, pound. Its Obverse and reverse, obverse features the profile of the current Monarchy of the United Kingdom, Monarch since the coin's introduction in 1969. , five different royal portraits have been used. there were an estimated 920 million 50p coins in circulation. The coin has proved popular with coin collectors leading to numerous differing designs for both commemorative and circulating coins. Fifty pence coins are legal tender for amounts up to the sum of £10 when offered in repayment of a debt; however, the coin's legal tender status is not normally relevant for everyday transactions. History In 1967 the Deputy Master of the Royal Mint approached the Decimal Currency Board to ask for their advice on the introduction of a new coin. The 10-shilling note then in use was lastin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twenty Pence (British Coin)
The United Kingdom, British decimal twenty pence coin (often shortened to 20p in writing and speech) is a denomination of Coins of the United Kingdom, sterling coinage worth of a Pound sterling, pound. Like the Fifty pence (British coin), 50p coin, it is an Curve of constant width, equilateral curve heptagon. Its obverse has featured the profile of Queen Elizabeth II since the coin's introduction on 9 June 1982. Four different portraits of the Queen have been used; the latest design by Jody Clark was introduced in 2015. The second and current reverse (as of 2019), featuring a segment of the Royal coat of arms of the United Kingdom, Royal Shield, was introduced in 2008. As of March 2014 there were an estimated 2,765 million 20p coins in circulation, with an estimated face value of £553.025 million. Of this estimated number, between 50,000 and 200,000 of these coins are undated Mule (coin), mule coins minted in 2008 after the dies for the old and new designs were accidentally mixe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reinhardt Polygon
In geometry, a Reinhardt polygon is an equilateral polygon inscribed in a Reuleaux polygon. As in the regular polygons, each vertex of a Reinhardt polygon participates in at least one defining pair of the diameter of the polygon. Reinhardt polygons with n sides exist, often with multiple forms, whenever n is not a power of two. Among all polygons with n sides, the Reinhardt polygons have the largest possible perimeter for their diameter, the largest possible width for their diameter, and the largest possible width for their perimeter. They are named after Karl Reinhardt, who studied them in 1922. Definition and construction A Reuleaux polygon is a convex shape with circular-arc sides, each centered on a vertex of the shape and all having the same radius; an example is the Reuleaux triangle. These shapes are curves of constant width. Some Reuleaux polygons have side lengths that are irrational multiples of each other, but if a Reuleaux polygon has sides that can be partitioned ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reinhardt 15-gons
Reinhardt may refer to: * Reinhardt University, Waleska, Georgia, USA People * Reinhardt (surname) * Reinhardt Kristensen, Danish invertebrate biologist * Reinhardt Rahr, American politician Fictional characters * Reinhardt (''Overwatch''), a character from the 2016 video game * Reinhardt, a character from '' Fire Emblem: Thracia 776'' See also * Reinhard * Reinhart Reinhart is a given name or surname, and may refer to: Surname *Anna Barbara Reinhart (1730–1796), Swiss mathematician * Annie Reinhart (1942–2004), American politician from Missouri * Art Reinhart (1899–1946), Major League Baseball pitc ... * Rinehart * Operation Reinhard, a particularly deadly part of the Holocaust {{Disambig, given name Germanic given names German masculine given names Dutch masculine given names ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convex Polygon
In geometry, a convex polygon is a polygon that is the boundary of a convex set. This means that the line segment between two points of the polygon is contained in the union of the interior and the boundary of the polygon. In particular, it is a simple polygon (not self-intersecting). Equivalently, a polygon is convex if every line that does not contain any edge intersects the polygon in at most two points. A strictly convex polygon is a convex polygon such that no line contains two of its edges. In a convex polygon, all interior angles are less than or equal to 180 degrees, while in a strictly convex polygon all interior angles are strictly less than 180 degrees. Properties The following properties of a simple polygon are all equivalent to convexity: *Every internal angle is strictly less than 180 degrees. *Every point on every line segment between two points inside or on the boundary of the polygon remains inside or on the boundary. *The polygon is entirely contained in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
