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Theodor Spieker
Theodor Spieker (8 August 1823 – 9 April 1913) was a German mathematician, a teacher at a gymnasium in Potsdam. Spieker's geometry textbook (Verlag von August Stein, Potsdam, 1862) was republished in many editions. A copy of this textbook was given to Albert Einstein by his tutor when Einstein was twelve, and quickly led Einstein to become interested in higher mathematics.. Spieker is the namesake of the Spieker circle In geometry, the incircle of the medial triangle of a triangle is the Spieker circle, named after 19th-century German geometer Theodor Spieker. Its center, the Spieker center, in addition to being the incenter of the medial triangle, is the cen ... of a triangle (the circle inscribed in its medial triangle) and the Spieker center (the center of the Spieker circle). References {{DEFAULTSORT:Spieker, Theodor 1823 births 1913 deaths 19th-century German mathematicians ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gymnasium (school)
''Gymnasium'' (and variations of the word) is a term in various European languages for a secondary school that prepares students for higher education at a university. It is comparable to the US English term '' preparatory high school''. Before the 20th century, the gymnasium system was a widespread feature of educational systems throughout many European countries. The word (), from Greek () 'naked' or 'nude', was first used in Ancient Greece, in the sense of a place for both physical and intellectual education of young men. The latter meaning of a place of intellectual education persisted in many European languages (including Albanian, Bulgarian, Estonian, Greek, German, Hungarian, the Scandinavian languages, Dutch, Polish, Czech, Serbo-Croatian, Macedonian, Slovak, Slovenian and Russian), whereas in other languages, like English (''gymnasium'', ''gym'') and Spanish (''gimnasio''), the former meaning of a place for physical education was retained. School ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potsdam
Potsdam () is the capital and, with around 183,000 inhabitants, largest city of the German state of Brandenburg. It is part of the Berlin/Brandenburg Metropolitan Region. Potsdam sits on the River Havel, a tributary of the Elbe, downstream of Berlin, and lies embedded in a hilly morainic landscape dotted with many lakes, around 20 of which are located within Potsdam's city limits. It lies some southwest of Berlin's city centre. The name of the city and of many of its boroughs are of Slavic origin. Potsdam was a residence of the Prussian kings and the German Kaiser until 1918. Its planning embodied ideas of the Age of Enlightenment: through a careful balance of architecture and landscape, Potsdam was intended as "a picturesque, pastoral dream" which would remind its residents of their relationship with nature and reason. The city, which is over 1000 years old, is widely known for its palaces, its lakes, and its overall historical and cultural significance. Landmarks include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albert Einstein
Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory of relativity, but he also made important contributions to the development of the theory of quantum mechanics. Relativity and quantum mechanics are the two pillars of modern physics. His mass–energy equivalence formula , which arises from relativity theory, has been dubbed "the world's most famous equation". His work is also known for its influence on the philosophy of science. He received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect", a pivotal step in the development of quantum theory. His intellectual achievements and originality resulted in "Einstein" becoming synonymous with "genius". In 1905, a year sometimes described as his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spieker Circle
In geometry, the incircle of the medial triangle of a triangle is the Spieker circle, named after 19th-century German geometer Theodor Spieker. Its center, the Spieker center, in addition to being the incenter of the medial triangle, is the center of mass of the uniform-density boundary of triangle. The Spieker center is also the point where all three cleavers of the triangle (perimeter bisectors with an endpoint at a side's midpoint) intersect each other. History The Spieker circle and Spieker center are named after Theodor Spieker, a mathematician and professor from Potsdam, Germany. In 1862, he published , dealing with planar geometry. Due to this publication, influential in the lives of many famous scientists and mathematicians including Albert Einstein, Spieker became the mathematician for whom the Spieker circle and center were named. Construction To find the Spieker circle of a triangle, the medial triangle must first be constructed from the midpoints of each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medial Triangle
In Euclidean geometry, the medial triangle or midpoint triangle of a triangle is the triangle with vertices at the midpoints of the triangle's sides . It is the case of the midpoint polygon of a polygon with sides. The medial triangle is not the same thing as the median triangle, which is the triangle whose sides have the same lengths as the medians of . Each side of the medial triangle is called a ''midsegment'' (or ''midline''). In general, a midsegment of a triangle is a line segment which joins the midpoints of two sides of the triangle. It is parallel to the third side and has a length equal to half the length of the third side. Properties The medial triangle can also be viewed as the image of triangle transformed by a homothety centered at the centroid with ratio -1/2. Thus, the sides of the medial triangle are half and parallel to the corresponding sides of triangle ABC. Hence, the medial triangle is inversely similar and shares the same centroid and medians ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spieker Center
In geometry, the Spieker center is a special point associated with a plane triangle. It is defined as the center of mass of the perimeter of the triangle. The Spieker center of a triangle is the center of gravity of a homogeneous wire frame in the shape of . The point is named in honor of the 19th-century German geometer Theodor Spieker. The Spieker center is a triangle center and it is listed as the point ''X''(10) in Clark Kimberling's Encyclopedia of Triangle Centers. Location The following result can be used to locate the Spieker center of any triangle. :The Spieker center of triangle is the incenter of the medial triangle of . That is, the Spieker center of is the center of the circle inscribed in the medial triangle of . This circle is known as the Spieker circle. The Spieker center is also located at the intersection of the three cleavers of triangle . A cleaver of a triangle is a line segment that bisects the perimeter of the triangle and has one endpoint at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1823 Births
Eighteen or 18 may refer to: * 18 (number), the natural number following 17 and preceding 19 * one of the years 18 BC, AD 18, 1918, 2018 Film, television and entertainment * ''18'' (film), a 1993 Taiwanese experimental film based on the short story ''God's Dice'' * ''Eighteen'' (film), a 2005 Canadian dramatic feature film * 18 (British Board of Film Classification), a film rating in the United Kingdom, also used in Ireland by the Irish Film Classification Office * 18 (''Dragon Ball''), a character in the ''Dragon Ball'' franchise * "Eighteen", a 2006 episode of the animated television series '' 12 oz. Mouse'' Music Albums * ''18'' (Moby album), 2002 * ''18'' (Nana Kitade album), 2005 * '' 18...'', 2009 debut album by G.E.M. Songs * "18" (5 Seconds of Summer song), from their 2014 eponymous debut album * "18" (One Direction song), from their 2014 studio album ''Four'' * "18", by Anarbor from their 2013 studio album ''Burnout'' * "I'm Eighteen", by Alice Cooper common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1913 Deaths
Events January * January 5 – First Balkan War: Battle of Lemnos (1913), Battle of Lemnos – Greek admiral Pavlos Kountouriotis forces the Turkish fleet to retreat to its base within the Dardanelles, from which it will not venture for the rest of the war. * January 13 – Edward Carson founds the (first) Ulster Volunteers, Ulster Volunteer Force, by unifying several existing Ulster loyalism, loyalist militias to resist home rule for Ireland. * January 23 – 1913 Ottoman coup d'état: Ismail Enver comes to power. * January – Stalin (whose first article using this name is published this month) travels to Vienna to carry out research. Until he leaves on February 16 the city is home simultaneously to him, Hitler, Trotsky and Josip Broz Tito, Tito alongside Alban Berg, Berg, Freud and Jung and Ludwig Wittgenstein, Ludwig and Paul Wittgenstein. February * February 1 – New York City's Grand Central Terminal, having been rebuilt, reopens as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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