Circle - Blogi - Phil Decker - Ihmiset - Älypää ilmaiset nettipelit ja tietovisat

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Blogi aloitettu: 25.5.2007
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• Circle2.9.2012 klo 13:55

  A circle is a simple shape of Euclidean geometry that is the set of points in the plane that are equidistant from a given point, the centre. The distance between any of the points and the centre is called the radius.The word "circle" derives from the Greek, kirkos "a circle," from the base ker- which means to turn or bend. The origins of the words "circus" and "circuit" are closely related.

  The circle has been known since before the beginning of recorded history. Natural circles would have been observed, such as the Moon, Sun, and a short plant stalk blowing in the wind on sand, which forms a circle shape in the sand. The circle is the basis for the wheel, which, with related inventions such as gears, makes much of modern civilisation possible. In mathematics, the study of the circle has helped inspire the development of geometry, astronomy, and calculus.

  Early science, particularly geometry and astrology and astronomy, was connected to the divine for most medieval scholars, and many believed that there was something intrinsically "divine" or "perfect" that could be found in circles.

  
  

  Some highlights in the history of the circle are:

  1700 BCE The Rhind papyrus gives a method to find the area of a circular field. The result corresponds to 256 / 81 (3.16049...) as an approximate value of pi ..

  300 BCE  Book 3 of Euclid's Elements deals with the properties of circles.

  In Plato's Seventh Letter there is a detailed definition and explanation of the circle. Plato explains the perfect circle, and how it is different from any drawing, words, definition or explanation.

  1880 CE Lindemann proves that pi is transcendental, effectively settling the millennia-old problem of squaring the circle.

   

  Squaring the circle is a problem proposed by ancient geometers. It is the challenge of constructing a square with the same area as a given circle by using only a finite number of steps with compass and straightedge. More abstractly and more precisely, it may be taken to ask whether specified axioms of Euclidean geometry concerning the existence of lines and circles entail the existence of such a square.

  (Wikipedia)

  

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