Forum Geometricorum
Volume 18 (2018)

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1.    Stefan Liebscher and Dierck-E. Liebscher, The relativity of conics and circles, 1--6.

     2.  Carl Eberhart, Revisiting the quadrisection problem of Jacob Bernoulli, 7--16.

     3.  C. E. Garza-Hume, Maricarmen C. Jorge, and Arturo Olvera, Areas and shapes of planar irregular polygons, 17--36.

     4.  Samuel G. Moreno and Esther M. García--Caballero, Irrationality of √2: Yet another visual proof, 37--38.

     5.  Manfred Pietsch, Two hinged regular n-sided polygons, 39--42.

     6.  Hiroshi Okumura, A remark on the arbelos and the regular star polygon, 43--44.

     7.  Lubomir P. Markov, Revisiting the infinite surface area of Gabriel's horn, 45--46.

     8.  Giovanni Lucca, Integer sequences and circle chains inside a circular segment, 47--55.

     9.  Michel Bataille, On the extrema of some distance ratios, 57--62.

   10.  Apostolos Hadjidimos, Twins of Hofstadter elements, 63--70.

   11.  Li Zhou, Primitive Heronian triangles with integer inradius and exradii, 71--77.

   12.  Francisco Javier García Capitán, A family of triangles for which two specific triangle centers have the same coordinates, 79--82.

   13.  Robert Bosch, A new proof of  Erdős-Mordell inequality, 83--86.

   14.  Paris Pamfilos, Parabola conjugate to rectangular hyperbola, 87--92.

   15.  Gerasimos T. Soldatos, A toroidal approach to the doubling of the cube, 93--97.

   16.  Hiroshi Okumura and Saburou Saitoh, Remarks for the twin circles of Archimedes in a skewed arbelos, 99--102.

   17.  (Retracted) Sándor Nagydobai Kiss, On the cyclic quadrilaterals with the same Varignon parallelogram, 103--113.

   18.  Gábor Gévay, An extension of Miquel's six-circles theorem, 115--118.

   19.  Nicholas D. Brubaker,  Jasmine Camero,  Oscar Rocha Rocha,  Roberto Soto, and Bogdan D. Suceavǎ, A curvature invariant inspired by Leonhard Euler's inequality R  ≥ 2r, 119--127.

   20.  Michel Bataille, Constructing a triangle from two vertices and the symmedian point, 129--133.

   21.  Eugen J. Ionaşcu, The ``circle" of Apollonius  in Hyperbolic Geometry, 135--140.

   22.  Mark Shattuck, A geometric inequality for cyclic quadrilaterals, 141--154. 

   23.  Hiroshi Okumura and Saburou Saitoh, Harmonic mean and division by zero, 155--159.

   24.  Paris Pamfilos, Rectangles circumscribing a quadrangle, 161--184.

   25.  Mihály Bencze and Marius Drǎgan, The Blundon theorem in an acute triangle and some consequences, 185--194.

   26.  Purevsuren Damba and Uuganbaatar Ninjbat, Side disks of a spherical great polygon,  195--201.

   27.  Nikolaos Dergiades, Parallelograms inscribed in convex quadrangles, 203 --218.

   28.  Mohammad K. Azarian, ``A Study of Risāla al-Watar wa'l Jaib'' (The Treatise on  the Chord and Sine): Revisited, 219--222.

   29.  Blas Herrera, Algebraic equations of all involucre conics in the configuration of the c-inscribed equilateral triangles of a triangle, 223 --238.

   30.  Tran Quang Hung, A construction of the golden ratio in an arbitrary triangle, 239--244.

   31.  Martina Stepanova, New Constructions of Triangle from α, b-c, t_A, 245--250.

   32.  Robert Bosch, A new proof of Pitot theorem by AM-GM inequality, 251--253.

   33.  John Donnelly, A model of continuous plane geometry that is nowhere geodesic, 255--273.

   34.  John Donnelly, A model of nowhere geodesic plane geometry in which the triangle inequality fails everywhere, 275--296.

   35.  Omid Ali Shahni Karamzadeh, Is the mystery of Morley's trisector theorem resolved ? 297--306.

   36.  Floor van Lamoen, A synthetic proof of the equality of iterated Kiepert triangles K(φ,ψ) = K(ψ,φ), 307--308.

   37.  Şahlar Meherrem, Gizem Günel Açıksöz, Serenay Şen, Zeynep Sezer, and Güneş Başkes, Geometric inequalities in pedal quadrilaterals, 309--320.

   38.  Paris Pamfilos, Self-pivoting convex  quadrangles, 321--347.

   39.  Floor van Lamoen, Orthopoles and variable flanks, 349--351.

   40.  Nikolaos Dergiades and Tran Quang Hung, Simple proofs of Feuerbach's Theorem and Emelyanov's Theorem, 353--359.

   41.  Roger C. Alperin, Pedals of the Poncelet pencil and Fontené points, 361--365.

   42,  Francisco Javier García Capitán, Circumconics with asymptotes making a given angle, 367--370.

   43.  Yong Zhang, Junyao Peng, and Jiamin Wang, Integral triangles and trapezoids pairs with a common area and a common perimeter, 371--380.

   44.  Giuseppina Anatriello, Francesco Laudano, and Giovanni Vincenzi, Pairs of congruent-like quadrilaterals that are not congruent, 381--400.

   45.  Gábor Gévay, A remarkable theorem on eight circles, 401--408.

   46.  Hiroshi Okumura, An analogue to Pappus chain theorem with division by zero, 409--412.

   47.  Rogério César dos Santos, Polygons on the sides of an octagon, 413--418.

   48.  Stefan Liebscher and Dierck E.-Liebscher, The love for the three conics, 419--430.

   49.  Gerasimos T. Soldatos, A polynomial approach to the ``Bloom'' of Thymaridas and the Apollonius' circle, 431--433.