December 26, 2004 |
Droz-Farny Circles |

December 25, 2004 |
Perpendicular Bisectors in an Inscriptible Quadrilateral II |

December 24, 2004 |
Angle Bisectors and Perpendiculars in a Quadrilateral |

December 23, 2004 |
Perpendicular Bisectors in an Inscriptible Quadrilateral |

December 21, 2004 |
Droz-Farny Line Theorem |

December 19, 2004 |
Reflections of a Point on the Circumcircle |

December 18, 2004 |
Reflections of a Line Through the Orthocenter |

December 16, 2004 |
Reflections of the Orthocenter |

December 12, 2004 |
Intersecting Chords Theorem |

December 10, 2004 |
Tangent and Secant |

December 9, 2004 |
Isogonal and Isotomic Conjugalities |

December 8, 2004 |
Squares Inscribed In a Triangle III |

December 7, 2004 |
Square Inscribed in a Triangle II |

December 6, 2004 |
Cevian Triangle |

November 29, 2004 |
Convex Polygon Is the Intersection of Half Planes |

November 26, 2004 |
Pedal Polygons |

November 17, 2004 |
Sierpinski's Gasket and Dihedral Symmetry |

November 10, 2004 |
Rolle's and Mean Value Theorems |

November 8, 2004 |
Addition and Subtraction of Functions |

November 5, 2004 |
The Length of the diagonal of the unit square equals the square root of 2 |

November 4, 2004 |
Suan Pan in Various Number Systems |

November 3, 2004 |
Soroban in Various Number Systems |

November 2, 2004 |
Three Similar Polygons |

October 31, 2004 |
Color Cycling on the Mandelbrot Set |

October 22, 2004 |
Venn Diagrams |

October 14, 2004 |
Distributive Law |

October 12, 2004 |
Circles On Cevians |

October 9, 2004 |
Three Similar Triangles II |

October 8, 2004 |
Two Squares and Another Square and Directly Similar Figures |

October 6, 2004 |
Three Similar Triangles |

October 5, 2004 |
Four Circles In a Triangle |

October 4, 2004 |
Monotone Number Sequences |

September 28, 2004 |
Stick Broken Into Three Pieces (Cartesian Coordinates) |

September 23, 2004 |
Proof #44 of the Pythagorean Theorem |

September 18, 2004 |
Equilateral Triangles On Sides of a Parallelogram |

September 17, 2004 |
Anticomplementary Triangle Surprise |

September 15, 2004 |
Three Isosceles Triangles |

September 14, 2004 |
A Tool for Constructing Orthogonal Latin Squares |

September 12, 2004 |
Tangents and Diagonals in Cyclic Quadrilateral |

September 10, 2004 |
Six Circles Theorem (Elkies) |

September 9, 2004 |
Six Circles Theorem (Evelyn) |

September 8, 2004 |
Stick Broken Into Three Pieces (Trilinear Coordinates) |

September 5, 2004 |
Sam Loyd's Son's Dissection |

September 4, 2004 |
Langman's Paradox |

September 3, 2004 |
Curry's Paradox |

August 31, 2004 |
Upgraded Tower of Hanoi |

August 29, 2004 |
Monge via Desargues II |

August 28, 2004 |
Radical Axis and Center, an Application |

August 27, 2004 |
Monge via Desargues |

August 25, 2004 |
Counting Triangles |

August 7, 2004 |
Radical Center |

August 6, 2004 |
Flipping Items Simultaneously II |

August 5, 2004 |
Flipping Items Simultaneously |

July 24, 2004 |
Cevian Nest |

July 19, 2004 |
Wythoff's Nim II |

July 18, 2004 |
Grundy's Game |

July 12, 2004 |
Segment Trisection |

July 5, 2004 |
Upgraded the Farmer and Wife To Catch Rooster and Hen puzzle |

June 21, 2004 |
Upgraded the Kayles game |

June 20, 2004 |
Rouse Ball's Fallacy |

June 18, 2004 |
Four Incident Circles |

June 17, 2004 |
Proizvolov's Identity |

June 15, 2004 |
Plainim Misère |

June 12, 2004 |
Touching Circles |

June 9, 2004 |
Symmedian and the Tangents |

June 8, 2004 |
Symmedian and 2 Antiparallels |

June 7, 2004 |
Symmedian and Antiparallel |

June 6, 2004 |
Three Tangents Theorem |

June 5, 2004 |
A Tangent in Concurrency |

June 1, 2004 |
Chvatal's Art Gallery Theorem |

May 30, 2004 |
According to the Rules |

May 18, 2004 |
Scoring Misère |

May 6, 2004 |
Vecten's Collinearity |

April 5, 2004 |
Inversion in the Incircle |

April 2, 2004 |
Carnot's Theorem |

March 28, 2004 |
Viviani's Theorem |

March 27, 2004 |
Nobbs' Points, Gergonne Line |

March 25, 2004 |
Tromino Puzzle |

March 24, 2004 |
Tiling a Triangulated Hexagon |

March 22, 2004 |
Polygons Formed by Perpendicular Bisectors |

March 21, 2004 |
Quadrilaterals Formed by Perpendicular Bisectors |

March 18, 2004 |
Equilateral Triangles on Sides of a Quadrilateral |

March 14, 2004 |
Four Pegs That Form a Square |

March 7, 2004 |
The Parabola |

February 26, 2004 |
Updated the Twelve Matchsticks Area Puzzle |

February 25, 2004 |
Updated the page on solving x^{x3} = 3 |

February 14, 2004 |
Solution to the BiColor Tower of Hanoi puzzle, by N. Bowler |

February 2, 2004 |
Collinearity in Bicentric Quadrilaterals |

February 1, 2004 |
Projective Collinearity in a Quadrilateral |

January 31, 2004 |
Easy Construction of Bicentric Quadrilateral II |

January 30, 2004 |
Easy Construction of Bicentric Quadrilateral |

January 29, 2004 |
Squares on Sides of a Quadrilateral |

January 27, 2004 |
Three Incircles in a Triangle |

January 25, 2004 |
Two Quadrilaterals |

January 24, 2004 |
Diagonals in a Cyclic Quadrilateral |

January 21, 2004 |
Ceva in Circumscribed Quadrilateral |

January 10, 2004 |
Zaslavsky's theorem |

January 4, 2004 |
Erro Ergo Disco |