A simple vector proof of Feuerbach's theorem - Michael J. G. Scheer The celebrated theorem of Feuerbach states that the nine-point circle of a...
A spatial view of the second Lemoine circle - Floor van Lamoen We consider circles in the plane as orthogonal projections of spheres in three...
The lemniscatic chessboard - Joel C. Langer and David A. Singer Unit speed parametrization of the lemniscate of Bernoulli is given by a simple...
On a certain cubic geometric inequality - Toufik Mansour and Mark Shattuck We provide a proof of a geometric inequality relating the cube of the...
When is a tangential quadrilateral a kite? - Martin Josefsson We prove 13 necessary and sufficient conditions for a tangential quadrilateral to...
The area of a bicentric quadrilateral - Martin Josefsson We review and prove a total of nine different formulas for the area of a bicentric...
On a triad of circles tangent to the circumcircle and the sides at their midpoints - Luis Gonzalez With synthetic methdos, we study, for a given...
More on twin circles of the skewed arbelos - Hiroshi Okumura Two pairs of congruent circles related to the skewed arbelos are given. [IMG]...
More on the extension of Fermat's problem - Nguyen Minh Ha and Bui Viet Loc We give an elementary and complete solution to the Fermat problem...
Solving Euler's triangle problems with Poncelet's pencil - Roger C. Alperin We determine the unique triangle given its orthocenter, circumcenter...
The Droz-Farny circles of a convex quadrilateral - Maria Flavia Mammana, Biagio Micale and Mario Pennisi The Droz-Farny circles of a triangle are...
On a theorem of intersecting conics - Darren C. Ong Given two conics over an infinite field that intersect at the origin, a line through the...
Perspective isoconjugate triangle pairs, Hofstadter pairs, and crosssums on the nine-point circle - Peter J. C. Moses and Clark Kimberling The...
More characterizations of tangential quadrilaterals - Martin Josefsson In this paper we will prove several not so well known conditions for a...
On the foci of circumparabolas - Michel Bataille We establish some results about the foci of the infinitely many parabolas passing through three...
Another simple construction of the golden section - Michel Bataille Given an equilateral triangle ABC, erect a square BCDE externally on the side...
A simple construction of the golden section - Jo Niemeyer Three equal segments A_1B_1, A_2B_2, A_3B_3 are positioned in such a way that the...
Triangles with given incircle and centroid - Paris Pamfilos In this article we study the set of triangles sharing a common incircle and a common...
Translation of Fuhrmann's Sur un nouveau cercle associe a un triangle - Jan Vonk and J. Chris Fisher We provide a translation (from the French)...
The incenter and an excenter as solutions to an extremal problem - Arie Bialostocki and Dora Bialostocki Given a triangle ABC with a point X on...
