Hyperbolas and orthologic triangles.
Čerin, Z. (1997)
Mathematica Pannonica
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Čerin, Z. (1997)
Mathematica Pannonica
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Bukor, József (2008)
Annales Mathematicae et Informaticae
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Roland Coghetto (2016)
Formalized Mathematics
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We introduce, using the Mizar system [1], some basic concepts of Euclidean geometry: the half length and the midpoint of a segment, the perpendicular bisector of a segment, the medians (the cevians that join the vertices of a triangle to the midpoints of the opposite sides) of a triangle. We prove the existence and uniqueness of the circumcenter of a triangle (the intersection of the three perpendicular bisectors of the sides of the triangle). The extended law of sines and the formula...
Paulus Gerdes (2003)
Visual Mathematics
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Miguel de Guzmán (2001)
RACSAM
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A simple proof is presented of a famous, and difficult, theorem by Jakob Steiner. By means of a straightforward transformation of the triangle, the proof of the theorem is reduced to the case of the equilateral triangle. Several relations of the Steiner deltoid with the Feuerbach circle and the Morley triangle appear then as obvious.
Kolar-Begović, Z., Kolar-Šuper, R., Beban-Brkić, J., Volenec, V. (2006)
Mathematica Pannonica
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Roland Coghetto (2015)
Formalized Mathematics
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Morley’s trisector theorem states that “The points of intersection of the adjacent trisectors of the angles of any triangle are the vertices of an equilateral triangle” [10]. There are many proofs of Morley’s trisector theorem [12, 16, 9, 13, 8, 20, 3, 18]. We follow the proof given by A. Letac in [15].
Stammler, Ludwig (1997)
Beiträge zur Algebra und Geometrie
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Shen, Yujin, Tolosa, Juan (2008)
International Journal of Mathematics and Mathematical Sciences
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Tomohide Hashiba, Yuta Nakagawa, Toshiyuki Yamauchi, Hiroshi Matsui, Satoshi Hashiba, Daisuke Minematsu, Munetoshi Sakaguchi, Ryohei Miyadera (2007)
Visual Mathematics
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Roland Coghetto (2014)
Formalized Mathematics
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We calculate the values of the trigonometric functions for angles: [XXX] , by [16]. After defining some trigonometric identities, we demonstrate conventional trigonometric formulas in the triangle, and the geometric property, by [14], of the triangle inscribed in a semicircle, by the proposition 3.31 in [15]. Then we define the diameter of the circumscribed circle of a triangle using the definition of the area of a triangle and prove some identities of a triangle [9]. We conclude by...
Kynčl, Jan, Tancer, Martin (2008)
The Electronic Journal of Combinatorics [electronic only]
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Roland Coghetto (2016)
Formalized Mathematics
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We introduce the altitudes of a triangle (the cevians perpendicular to the opposite sides). Using the generalized Ceva’s Theorem, we prove the existence and uniqueness of the orthocenter of a triangle [7]. Finally, we formalize in Mizar [1] some formulas [2] to calculate distance using triangulation.