On the intersections of the incircle and the cevian circumcircle of the incenter - Luis Gonzalez and Cosmin Pohoata We give a characterization of...
Three conics derived from perpendicular lines - Alberto Mendoza Given a triangle ABC and a generic point P on its plain, we consider the...
Reflection triangles and their iterates - Gregoire Nicollier By reflecting each vertex of a triangle in the opposite side one obtains the...
A new proof of Yun's inequality or bicentric quadrilaterals - Martin Josefsson We give a new proof of a recent inequality for bicentric...
Similar metric characterizations of tangential and extangential quadrilaterals - Martin Josefsson We prove five necessary and sufficient...
Properties of valtitudes and vaxes of a convex quadrilateral - Maria Flavia Mammana, Biagio Micale, and Mario Pennisi We introduce the vaxes...
The isosceles trapezoid and its dissecting similar triangles - Larry Hoehn Isosceles trapezoids are dissected into three similar triangles and...
More integer triangles with R div r=N - John F. Goehl Given an integer-sided triangle with an integer ratio of the radii of the circumcircle and...
Characterizations of orthodiagonal quadrilaterals - Martin Josefsson We prove ten necessary and sufficient conditions for a convex quadrilateral...
Generalization and extension of the Wallace theorem - Gotthard Weise In the Wallace theorem we replace the projection directions (altitudes of...
On six circumcenters and their concyclicity - Nikolas Dergiades, Francisco Javier Garcia Capitan, and Sung Hyun Lim Given triangle ABC, let P be...
Construction of circles through intercepts to paralells to cevians - Jean-Pierre Ehrmann, Francisco Javier Garcia Capitan, and Alexei Myakishev...
The golden section with a collapsible compass only - Nikolaos Dergiades and Paul Yiu With the use of a collapsible compass, we divide a given...
Golden sections in a regular hexagon - Quang Tuan Bui We relate a golden section associated with a regular hexagon to two recent simple...
Rational Steiner porism - Paul Yiu We establish formulas relating the radii of neighboring circles in a Steiner chain, a chain of mutually...
The distance from the incenter to the Euler line - William N. Franzsen It is well known that the incenter of a triangle lies on the Euler line if...
Cyclic quadrilaterals associated with squares - Mihai Cipu We discuss a family of problems asking to find the geometrical locus of points P in...
Collinearity of the first trisection points of cevian segments - Francisco Javier Garcia Capitan We show that the first trisection points of the...
The area of the diagonal point triangle - Martin Josefsson In this note we derive a formula for the area of the diagonal point triangle belonging...
A new formula concerning the diagonals and sides of a quadrilateral - Larry Hoehn We derive a formula relating the sides and diagonal sections of...
