Search Results: Excircle
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Incircle and excircles
Sabtu, 2026-05-30 07:14:14of the incircle is a triangle center called the triangle's incenter. An excircle or escribed circle of the triangle is a circle lying outside the triangle...
Click to read more »Ex-tangential quadrilateral
Minggu, 2025-04-06 13:36:27also been called an exscriptible quadrilateral. The circle is called its excircle, its radius the exradius and its center the excenter (E in the figure)...
Click to read more »Semiperimeter
Selasa, 2026-01-13 00:02:36{a+b+c}{2}}.} In any triangle, any vertex and the point where the opposite excircle touches the triangle partition the triangle's perimeter into two equal...
Click to read more »Circle
Minggu, 2026-05-17 11:07:46circles Schoch circles Woo circles Apollonius circle of the excircles Brocard circle Excircle Incircle Lemoine circle Lester circle Malfatti circles Mandart...
Click to read more »Nagel point
Senin, 2026-02-16 13:55:42TC be the extouch points in which the A-excircle meets line BC, the B-excircle meets line CA, and the C-excircle meets line AB, respectively. The lines...
Click to read more »Feuerbach point
Kamis, 2025-12-11 21:57:37states more generally that the nine-point circle is tangent to the three excircles of the triangle as well as its incircle. A very short proof of this theorem...
Click to read more »Triangle
Minggu, 2026-05-24 18:59:49excircles; they lie outside the triangle and touch one side, as well as the extensions of the other two. The centers of the incircles and excircles form...
Click to read more »Extended side
Senin, 2026-03-16 09:44:42corresponding extended base sides but not the base sides themselves. The excircles of a triangle, as well as the triangle's inconics that are not inellipses...
Click to read more »Extouch triangle
Rabu, 2025-12-03 22:24:20triangle of a triangle is formed by joining the points at which the three excircles touch the triangle. The vertices of the extouch triangle are given in...
Click to read more »Acute and obtuse triangles
Kamis, 2026-02-05 13:01:18{\displaystyle r^{2}+r_{a}^{2}+r_{b}^{2}+r_{c}^{2}<8R^{2},} in terms of the excircle radii ra , rb , and rc , again with the reverse inequality holding for...
Click to read more »Nine-point circle
Rabu, 2026-05-13 06:46:26triangle's nine-point circle is externally tangent to that triangle's three excircles and internally tangent to its incircle; this result is known as Feuerbach's...
Click to read more »Mixtilinear incircles of a triangle
Minggu, 2025-10-26 22:41:09incircles, one corresponding to each vertex. The A {\displaystyle A} -excircle of triangle A B C {\displaystyle ABC} is unique. Let Φ {\displaystyle \Phi...
Click to read more »Collinearity
Minggu, 2025-07-20 02:26:32collinearities. Any vertex, the tangency of the opposite side with an excircle, and the Nagel point are collinear in a line called a splitter of the triangle...
Click to read more »Quadratic equation
Rabu, 2026-06-03 08:00:47distance between the circumscribed circle's center and the center of the excircle of an ex-tangential quadrilateral. Critical points of a cubic function...
Click to read more »List of two-dimensional geometric shapes
Senin, 2026-06-01 14:01:16circle Circular triangle Reuleaux triangle Circumcircle Disc Incircle and excircles of a triangle Nine-point circle Circular sector Circular segment Crescent...
Click to read more »Pythagorean triple
Selasa, 2026-05-12 02:10:07three excircles are positive integers. Specifically, for a primitive triple the radius of the incircle is r = n(m − n), and the radii of the excircles opposite...
Click to read more »Apollonius point
Kamis, 2025-05-22 07:47:55points of tangency formed by the opposing excircle and a larger circle that is tangent to all three excircles. In the literature, the term "Apollonius...
Click to read more »Bevan point
Sabtu, 2025-12-27 22:51:36the Bevan circle, that is the circle through the centers of the three excircles of a triangle. The Bevan point of a triangle is the reflection of the...
Click to read more »Heron's formula
Rabu, 2026-05-13 05:33:40formula, for example using trigonometry as below, or the incenter and one excircle of the triangle, or as a special case of De Gua's theorem (for the particular...
Click to read more »Right triangle
Kamis, 2026-03-05 12:15:32right triangle equals the sum of the radii of the incircle and the three excircles: a + b + c = r + r a + r b + r c . {\displaystyle a+b+c=r+r_{a}+r_{b}+r_{c}...
Click to read more »Area of a triangle
Minggu, 2026-04-12 00:29:33r b , r c {\displaystyle r_{a},\,r_{b},\,r_{c}} are the radii of the excircles tangent to sides a, b, c respectively. We also have T = 1 2 D 2 ( sin...
Click to read more »Soddy circles of a triangle
Senin, 2026-05-11 04:51:41triple of circles having tangencies at the points where one of the three excircles is tangent to these lines. The pairs of tangent circles to these three...
Click to read more »Quadrilateral
Kamis, 2026-04-16 04:56:29Ex-tangential quadrilateral: the four extensions of the sides are tangent to an excircle. An equilic quadrilateral has two opposite equal sides that when extended...
Click to read more »Power center (geometry)
Senin, 2024-05-13 14:18:36circles. The Spieker center of a triangle is the radical center of its excircles. Several types of radical circles have been defined as well, such as the...
Click to read more »Bisection
Sabtu, 2026-02-28 14:22:37Construction of the center of a Thales' circle, Construction of the center of the Excircle of a triangle, Voronoi diagram boundaries consist of segments of such lines...
Click to read more »Thébault's theorem
Minggu, 2026-03-22 00:52:01"external" version of this theorem, where the incircle is replaced by an excircle and the two additional circles are external to the circumcircle, is found...
Click to read more »Incenter
Selasa, 2026-05-12 16:08:50distant from the lines, the excenters, which form the centers of the excircles of the given triangle. The incenter and excenters together form an orthocentric...
Click to read more »Tree of primitive Pythagorean triples
Rabu, 2026-03-25 15:34:21involves the excircles present at each node. The three children of any parent triangle “inherit” their inradii from the parent: the parent's excircle radii become...
Click to read more »Kite (geometry)
Jumat, 2026-04-10 05:52:431 + r 3 = r 2 + r 4 . {\displaystyle r_{1}+r_{3}=r_{2}+r_{4}.} If the excircles to the same four triangles opposite the vertex P {\displaystyle P} ...
Click to read more »Harcourt's theorem
Selasa, 2026-03-17 15:50:17times the altitude from that base. If the line is instead tangent to the excircle opposite, say, vertex A of the triangle, then − a a ′ + b b ′ + c c ′ =...
Click to read more »Triangle center
Jumat, 2026-03-20 01:31:15Intersection of the lines connecting each vertex to the point where an excircle touches the opposite side. X9 Mittenpunkt M ( b + c − a ) : ( c + a − b...
Click to read more »Orthocenter
Selasa, 2026-06-02 04:24:00the radius of the triangle's incircle, ra, rb, rc as the radii of its excircles, and R again as the radius of its circumcircle, the following relations...
Click to read more »Mandart inellipse
Jumat, 2025-08-15 12:19:46within the triangle, tangent to its sides at the contact points of its excircles (which are also the vertices of the extouch triangle and the endpoints...
Click to read more »Outline of geometry
Rabu, 2025-10-22 17:43:51of circle topics Thales' theorem Circumcircle Concyclic Incircle and excircles of a triangle Orthocentric system Monge's theorem Power center Nine-point...
Click to read more »Tangential quadrilateral
Jumat, 2026-01-09 22:50:02concerns the exradii ra, rb, rc, and rd in the same four triangles (the four excircles are each tangent to one side of the quadrilateral and the extensions of...
Click to read more »Lexell's theorem
Jumat, 2026-04-24 01:24:42circumscribing △ A ∗ B ∗ C {\displaystyle \triangle A^{*}B^{*}C} becomes an excircle l ′ {\displaystyle l'} of △ A ′ B ′ C ′ {\displaystyle \triangle A'B'C'}...
Click to read more »Integer triangle
Selasa, 2026-04-14 21:33:22(non-Pythagorean) triangles with integer radii for the incircle and each excircle. A family of decomposable ones is given by a = 4 n 2 {\displaystyle a=4n^{2}}...
Click to read more »Spieker center
Jumat, 2024-11-15 10:56:29b . {\displaystyle b+c:c+a:a+b.} S is the radical center of the three excircles. S is the cleavance center of triangle △ABC S is collinear with the incenter...
Click to read more »Orthocentric system
Selasa, 2025-07-15 20:20:01points. The common nine-point circle is tangent to all 16 incircles and excircles of the four triangles whose vertices form the orthocentric system. If...
Click to read more »Robert Baldwin Hayward
Selasa, 2026-01-20 18:49:34of his work on the method of moving axes. Hayward called a hyperbola an excircle in his Algebra of Coplanar Vectors and Trigonomety. Chapter 6 considered...
Click to read more »Triangle conic
Rabu, 2026-04-15 01:22:00Incircle and excircles...
Click to read more »L'Huilier's theorem
Minggu, 2025-11-23 23:54:24{\displaystyle r_{\text{A}},r_{\text{B}},r_{\text{C}}} be the radii of the three excircles. Then 1 r = 1 r A + 1 r B + 1 r C {\displaystyle {\frac {1}{r}}={\frac...
Click to read more »Encyclopedia of Triangle Centers
Selasa, 2026-02-10 15:21:28point X(9) Mittenpunkt symmedian point of the triangle formed by the centers of the three excircles X(10) Spieker center center of the Spieker circle...
Click to read more »Exsphere (polyhedra)
Kamis, 2026-06-04 02:44:27the adjacent faces internally. It is the 3-dimensional equivalent of the excircle. The sphere is more generally well-defined for any face which is a regular...
Click to read more »Tangent circles
Jumat, 2026-04-03 00:27:17tangency of the nine-point circle of a triangle with its incircle and excircles Descartes' theorem on the radii of four pairwise tangent circles Ford...
Click to read more »Trilinear coordinates
Jumat, 2026-06-05 13:16:40{\sqrt {z}}\cos {\frac {C}{2}}=0,} while the equation for, for example, the excircle adjacent to the side segment opposite vertex A can be written as ± − x...
Click to read more »Splitter (geometry)
Jumat, 2025-11-14 04:06:34triangle vertex lies at the point on the triangle's side where one of the excircles of the triangle is tangent to that side. This point is also called a splitting...
Click to read more »Problem of Apollonius
Jumat, 2026-05-22 22:43:07there are four solutions to the general LLL problem (the incircle and excircles of the triangle formed by the three lines). Points and lines may be viewed...
Click to read more »Concurrent lines
Jumat, 2026-04-24 23:32:45which connects a point of tangency of the circle to which the triangle's excircles are internally tangent, to the opposite vertex of the triangle. The two...
Click to read more »Clawson point
Kamis, 2025-06-19 21:49:07triangle and △TATBTC the triangle formed by the outer tangents to its three excircles. These two triangles are similar and the Clawson point is their center...
Click to read more »Formulas for generating Pythagorean triples
Rabu, 2026-05-27 20:42:07and its perimeter P, as well as the radii ri of its incircle and three excircles as follows: a = 2 q p b = q ′ p ′ c = p p ′ − q q ′ = q p ′ + q ′ p radii...
Click to read more »Heronian triangle
Kamis, 2026-04-23 08:27:56Heronian triangles, but additionally the centers of the incircle and excircles are at lattice points. See also Integer triangle § Heronian triangles...
Click to read more »List of triangle inequalities
Rabu, 2026-02-04 21:10:44three sides), the exradii ra, rb, and rc (each being the radius of an excircle tangent to side a, b, or c respectively and tangent to the extensions of...
Click to read more »List of triangle topics
Jumat, 2025-02-07 19:01:32Hyperbolic triangle (non-Euclidean geometry) Hypotenuse Incircle and excircles of a triangle Inellipse Integer triangle Isodynamic point Isogonal conjugate...
Click to read more »Central line (geometry)
Sabtu, 2026-01-31 11:08:33△I1I2I3 of △ABC. The triangle whose sidelines are externally tangent to the excircles of △ABC is the extangents triangle of △ABC. △ABC and its extangents triangle...
Click to read more »Isoperimetric point
Selasa, 2025-11-18 03:35:14is an isoperimetric point of △ABC in the sense of Veldkamp, then the excircles of triangles △PBC, △PCA, △PAB are pairwise tangent to one another and...
Click to read more »Yff center of congruence
Kamis, 2024-06-13 12:19:09triangle formed by the lines which are externally tangent to the three excircles of the Yff central triangle of △ABC. Let I be the incenter of △ABC. Let...
Click to read more »Circumconic and inconic
Jumat, 2026-05-22 20:50:18unique ellipse tangent to a triangle's sides at the contact points of its excircles Kiepert parabola Yff parabola Weisstein, Eric W. "Circumconic." From MathWorld--A...
Click to read more »Spieker circle
Minggu, 2025-06-22 16:19:21circle, centered at the Spieker center, which is orthogonal to the three excircles of the medial triangle. de Villiers, Michael (June 2006). "A generalisation...
Click to read more »Malfatti circles
Kamis, 2025-09-18 14:36:48connecting the tangencies of the Malfatti circles with the centers of the excircles of the triangle. Other triangle centers also associated with the Malfatti...
Click to read more »Inellipse
Senin, 2025-09-22 07:31:41of the triangle. It touches the sides at the points of contact of the excircles (see diagram). For s = | O B | 2 | O B | 2 + | A B | 2 , t = | O A |...
Click to read more »List of circle topics
Selasa, 2026-01-20 00:08:02Horocycle – Curve whose normals converge asymptotically Incircle and excircles of a triangle – Circles tangent to all three sides of a trianglePages...
Click to read more »Olry Terquem
Senin, 2026-04-20 16:14:23Feuerbach's theorem that the nine-point circle is tangent to the incircle and excircles of a triangle. Terquem's other contributions to mathematics include naming...
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