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Kite (geometry)
In Euclidean geometry, a kite is a quadrilateral with reflection symmetry across a diagonal. Because of this symmetry, a kite has two equal angles and two pairs of adjacent equal-length sides. Kites are also known as deltoids, but the word ''deltoid'' may also refer to a deltoid curve, an unrelated geometric object sometimes studied in connection with quadrilaterals.See H. S. M. Coxeter's review of in : "It is unfortunate that the author uses, instead of 'kite', the name 'deltoid', which belongs more properly to a curve, the three-cusped hypocycloid." A kite may also be called a dart, particularly if it is not convex. Every kite is an orthodiagonal quadrilateral (its diagonals are at right angles) and, when convex, a tangential quadrilateral (its sides are tangent to an inscribed circle). The convex kites are exactly the quadrilaterals that are both orthodiagonal and tangential. They include as special cases the right kites, with two opposite right angles; the rhombi, wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadrilateral
In geometry a quadrilateral is a four-sided polygon, having four edges (sides) and four corners (vertices). The word is derived from the Latin words ''quadri'', a variant of four, and ''latus'', meaning "side". It is also called a tetragon, derived from greek "tetra" meaning "four" and "gon" meaning "corner" or "angle", in analogy to other polygons (e.g. pentagon). Since "gon" means "angle", it is analogously called a quadrangle, or 4-angle. A quadrilateral with vertices A, B, C and D is sometimes denoted as \square ABCD. Quadrilaterals are either simple (not self-intersecting), or complex (self-intersecting, or crossed). Simple quadrilaterals are either convex or concave. The interior angles of a simple (and planar) quadrilateral ''ABCD'' add up to 360 degrees of arc, that is :\angle A+\angle B+\angle C+\angle D=360^. This is a special case of the ''n''-gon interior angle sum formula: ''S'' = (''n'' − 2) × 180°. All non-self-crossing quadrilaterals tile the pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isohedral Figure
In geometry, a tessellation of dimension (a plane tiling) or higher, or a polytope of dimension (a polyhedron) or higher, is isohedral or face-transitive if all its faces are the same. More specifically, all faces must be not merely congruent but must be ''transitive'', i.e. must lie within the same ''symmetry orbit''. In other words, for any two faces and , there must be a symmetry of the ''entire'' figure by translations, rotations, and/or reflections that maps onto . For this reason, convex isohedral polyhedra are the shapes that will make fair dice. Isohedral polyhedra are called isohedra. They can be described by their face configuration. An isohedron has an even number of faces. The dual of an isohedral polyhedron is vertex-transitive, i.e. isogonal. The Catalan solids, the bipyramids, and the trapezohedra are all isohedral. They are the duals of the (isogonal) Archimedean solids, prisms, and antiprisms, respectively. The Platonic solids, which are eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olaus Henrici
Olaus Magnus Friedrich Erdmann Henrici, Fellow of the Royal Society, FRS (9 March 1840, Meldorf, Duchy of Holstein – 10 August 1918, Chandler's Ford, Hampshire, England) was a German mathematician who became a professor in London. After three years as an apprentice in engineering, Henrici entered Karlsruhe Institute of Technology, Karlsruhe Polytechnium where he came under the influence of Alfred Clebsch who encouraged him in mathematics. He then went to Heidelberg where he studied with Otto Hesse. Henrici attained his Dr. phil. degree on 6 June 1863 at University of Heidelberg. He continued his studies in Berlin with Karl Weierstrass and Leopold Kronecker. He was briefly docent of mathematics and physics at the University of Kiel, but ran into financial difficulties. Henrici moved to London in 1865 where he worked as a private tutor. In 1869 Hesse introduced him to J. J. Sylvester who in turn brought him into contact with Arthur Cayley, William Kingdon Clifford, and Thomas Arc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kite (bird)
Kite () is the common name for certain birds of prey in the family Accipitridae, particularly in subfamilies Milvinae, [], and Perninae."kite". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2014. Web. 24 Nov. 2014 . The term is derived from Old English ''cȳta'' (“kite; bittern”), from the Proto-Indo-European root *''gū- '', "screech." Some authors use the terms "hovering kite" and "soaring kite" to distinguish between ''Elanus'' and the milvine kites, respectively. The group may also be differentiated by size, referring to milvine kites as "large kites", and elanine kites as "small kites". Species * Subfamily Elanid kite, Elaninae ** Genus ''Elanus'' *** Black-winged kite, ''Elanus caeruleus'' *** Black-shouldered kite, ''Elanus axillaris'' *** White-tailed kite, ''Elanus leucurus'' *** Letter-winged kite, ''Elanus scriptus'' ** Genus ''Chelictinia'' *** Scissor-tailed kite, ''Chelictinia riocourii'' ** Genus ''Gampsonyx'' ** ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kite
A kite is a tethered heavier than air flight, heavier-than-air or lighter-than-air craft with wing surfaces that react against the air to create Lift (force), lift and Drag (physics), drag forces. A kite consists of wings, tethers and anchors. Kites often have a bridle and tail to guide the face of the kite so the wind can lift it. Some kite designs don’t need a bridle; box kites can have a single attachment point. A kite may have fixed or moving anchors that can balance the kite. The name is derived from kite (bird), kite, the hovering bird of prey. The Lift (force), lift that sustains the kite in flight is generated when air moves around the kite's surface, producing low pressure above and high pressure below the wings. The interaction with the wind also generates horizontal Drag (physics), drag along the direction of the wind. The resultant force vector from the lift and drag force components is opposed by the tension of one or more of the rope, lines or tethers to which t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angle Bisector In geometry, bi |
