Square wreaths around hexagons - Floor van Lamoen We investigate the figures that arise when squares are attached to a triple of non-adjacent...
Two Brahmagupta problems - K. R. S. Sastry D. E. Smith reproduces two problems from Brahmagupta's work Kutakhadyaka (algebra) in his History of...
Intersecting circles and their inner tangent circle - Max A. Tran We derive the general equation for the radius of the inner tangent circle that...
On two remarkable lines related to a quadrilateral - Alexei Myakishev We study the Euler line of an arbitrary quadrilateral and the Nagel line of...
On the derivative of a vertex polynomial - James L. Parish A geometric characterization of the critical points of a complex polynomial f is...
Translated triangle perspective to a reference triangle - Clark Kimberling Suppose A, B, C, D, E, F are points and L is a line other than the...
A note on the barycentric square root of Kiepert perspectors - Khoa Lu Nguyen Let P be an interior point of a given triangle ABC. We prove that...
Formulas among diagonals in the regular polygon and the Catalan numbers - Matthew Hudelson We look at relationships among the lengths of...
On triangles with vertices on the angle bisectors - Eric Danneels We study interesting properties of triangleswhose vertices are on the three...
On butterflies inscribed in a quadrilateral - Zvonko Cerin We explore a configuration consisting of two quadrilaterals which share the...
The Droz-Farny theorem and related topics - Charles Thas At each point P of the Euclidean plane Pi , not on the sidelines of a triangle A_1A_2A_3...
On some theorems of Poncelet and Carnot - Huub van Kempen Some relations in a complete quadrilateral are derived. In connection with these...
A synthetic proof and generalization of Bellavitis' theorem - Nikolaos Dergiades In this note we give a synthetic proof of Bellavitis' theorem...
The Simmons conics - Bernard Gibert We study the conics introduced by T. C. Simmons and generalize some of their properties. [IMG]...
Pedals on circumradii and the Jerabek center - Quang Tuan Bui Given a triangle ABC, beginning with the orthogonal projections of the vertices on...
A simple perspectivity - Eric Danneels We construct a simple perspectivity that is invariant under isotomic conjugation. [IMG]...
The Feuerbach point and Euler lines - Bogdan Suceava and Paul Yiu Given a triangle, we construct three triangles associated its incircle whose...
A projectivity characterized by the Pythagorean relation - Wladimir Boskoff and Bogdan Suceava We study an interesting configuration that gives...
A theorem by Giusto Bellavitis on a class of quadrilaterals - Eisso J. Atzema In this note we prove a theorem on quadrilaterals first published...
A 4-step construction of the golden ratio - Kurt Hofstetter We construct, in 4 steps using ruler and compass, three points two of the the...
