• Thumbnail for Desargues's theorem
    In projective geometry, Desargues's theorem, named after Girard Desargues, states: Two triangles are in perspective axially if and only if they are in...
    16 KB (1,788 words) - 02:07, 29 March 2023
  • Thumbnail for Girard Desargues
    projective geometry. Desargues' theorem, the Desargues graph, and the crater Desargues on the Moon are named in his honour. Born in Lyon, Desargues came from a...
    6 KB (630 words) - 23:12, 26 February 2025
  • Thumbnail for Projective plane
    previous example, to obtain the projective Moulton plane. Desargues's theorem is not a valid theorem in either the Moulton plane or the projective Moulton...
    53 KB (6,933 words) - 22:59, 1 June 2025
  • Thumbnail for Desargues configuration
    Girard Desargues. The Desargues configuration can be constructed in two dimensions from the points and lines occurring in Desargues's theorem, in three...
    12 KB (1,490 words) - 19:06, 12 October 2024
  • Thumbnail for Pappus's hexagon theorem
    mathematician Gerhard Hessenberg proved that Pappus's theorem implies Desargues's theorem. In general, Pappus's theorem holds for some projective plane if and only...
    17 KB (2,865 words) - 22:17, 19 April 2025
  • Thumbnail for Projective space
    over a (commutative) field. Equivalently Pappus's hexagon theorem and Desargues's theorem are supposed to be true. A large part of the results remain...
    37 KB (5,670 words) - 20:15, 2 March 2025
  • Thumbnail for Finite geometry
    Desarguesian planes (those that are isomorphic with a PG(2, q)) satisfy Desargues's theorem and are projective planes over finite fields, but there are many...
    22 KB (2,841 words) - 13:36, 12 April 2024
  • over a (commutative) field. Equivalently Pappus's hexagon theorem and Desargues's theorem are supposed to be true. A large part of the results remain...
    30 KB (3,641 words) - 01:24, 25 February 2024
  • Thumbnail for Monge's theorem
    three dimensions. Monge's theorem can also be proved by using Desargues' theorem. Another easy proof uses Menelaus' theorem, since the ratios can be calculated...
    5 KB (665 words) - 06:19, 27 February 2025
  • satisfy Desargues' theorem (named after Girard Desargues), or in other words a plane that is not a Desarguesian plane. The theorem of Desargues is true...
    10 KB (1,174 words) - 02:55, 8 February 2024
  • Thumbnail for Pascal's theorem
    many interesting figures on parabolas and hyperbolas. Desargues's theorem Brianchon's theorem Unicursal hexagram Pascal 1640, translation Smith 1959...
    17 KB (2,198 words) - 00:12, 23 June 2024
  • De Bruijn–Erdős theorem (incidence geometry) De Gua's theorem (geometry) Desargues's theorem (projective geometry) Descartes's theorem (plane geometry)...
    78 KB (6,293 words) - 12:16, 2 May 2025
  • treatment of the geometries here possible seem to me desirable. Desargues's theorem: If two triangles lie on a plane such that the lines connecting corresponding...
    24 KB (3,535 words) - 02:17, 8 December 2024
  • like a "5"). Anamorphosis Curvilinear perspective Cutaway drawing Desargues's theorem Filmmaking Optical illusion Perspective control Perspective (graphical)...
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  • section Crystal Cuisenaire rods Desargues' theorem Right circular cone Hyperboloid Napkin ring problem Pappus's centroid theorem Paraboloid Polyhedron Defect...
    13 KB (914 words) - 10:26, 25 December 2024
  • Thumbnail for Poncelet–Steiner theorem
    Brianchon's theorem Ceva's theorem Desargues's theorem Menelaus's theorem Pascal's theorem Poncelet's closure theorem Ptolemy's theorem Apollonian circles...
    94 KB (13,108 words) - 16:40, 26 May 2025
  • Thumbnail for Perspective (geometry)
    ABC\doublebarwedge abc} to indicate that triangles ABC and abc are perspective. Desargues' theorem states that a central couple of triangles is axial. The converse statement...
    5 KB (640 words) - 03:13, 16 May 2025
  • Thumbnail for Bundle theorem
    According to Kahn's Theorem, it is fulfilled by "ovoidal" Möbius planes only; thus, it is the analog for Möbius planes of Desargues' Theorem for projective...
    5 KB (841 words) - 10:20, 14 July 2024
  • theorem is not necessarily true in all projective geometries; it is a property that some geometries satisfy but others don't. For example, Desargues'...
    3 KB (481 words) - 17:36, 4 February 2024
  • geometric system. Desargues's study on conic sections drew the attention of 16-year-old Blaise Pascal and helped him formulate Pascal's theorem. The works of...
    38 KB (5,099 words) - 22:20, 24 May 2025
  • projective plane in which the little Desargues theorem holds. This theorem states that a restricted form of Desargues' theorem holds for every line in the plane...
    4 KB (498 words) - 00:09, 6 January 2024
  • Thumbnail for Desargues graph
    The Desargues graph has one vertex for each point, one vertex for each line, and one edge for every incident point-line pair. Desargues' theorem, named...
    10 KB (1,203 words) - 11:19, 3 August 2024
  • have fixed points, so that the dual of A is A itself. For example, Desargues' theorem is self-dual in this sense under the standard duality in projective...
    53 KB (6,694 words) - 15:44, 28 January 2025
  • these are: Desargues' theorem ⇔ Converse of Desargues' theorem Pascal's theorem ⇔ Brianchon's theorem Menelaus' theorem ⇔ Ceva's theorem Not only statements...
    47 KB (5,688 words) - 02:41, 24 March 2025
  • spaces; such embeddability is a consequence of a property known as Desargues' theorem, not shared by all projective planes. In addition to its familiar...
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  • triangulation de Longchamps point Desargues' theorem Droz-Farny line theorem Encyclopedia of Triangle Centers Equal incircles theorem Equal parallelians point...
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  • significant for projective planes due to the universal validity of Desargues' theorem in higher dimensions. In contrast, the analytic approach is to define...
    12 KB (1,733 words) - 00:00, 22 November 2024
  • Hilbert, 1980 (1899). The Foundations of Geometry, 2nd edition, §22 Desargues Theorem, Chicago: Open Court Pambuccian, Victor; Schacht, Celia (2021), "The...
    14 KB (1,737 words) - 00:06, 27 December 2024
  • Thumbnail for Gerhard Hessenberg
    geometry, where he is known for proving that Desargues' theorem is a consequence of Pappus's hexagon theorem, and differential geometry where he is known...
    5 KB (394 words) - 03:49, 28 May 2025
  • Thumbnail for Geometric Algebra (book)
    skew field k. Axioms 4a and 4b are equivalent to Desargues' theorem. When Pappus's hexagon theorem holds in the affine geometry, k is commutative and...
    7 KB (910 words) - 01:24, 29 May 2025