Chronology of Updates

Note: I have placed chronology of updates for 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 and 2006 into separate files. Starting with 1997, the most recent entries appear topmost. Besides providing an insight into this site's evolution, chronology of updates may be used for word searches.

December 30 Horner's Method
December 29 Calculation of the Digits of pi (Faster Version)
December 28 Calculation of the Digits of pi by the Spigot Algorithm
December 24 It's All About Powers of 10
December 24 Four Pedal Circles
December 23 Griffiths Points in Cyclic Quadrilateral
December 22 Added a proof of Griffiths' Theorem
December 17 Nine Point Circle II
December 16 Ducci Sequences
December 13 The Basic Rules of Counting
December 13 The Deadly Parallel
December 12 From Foci to a Tangent in Ellipse
December 11 Harmonic Serires And Its Parts
December 11 Infinitude of Primes Via Harmonic Series
December 6 La Hire's Theorem in Ellipse
December 6 Σ2-n = Σn·2-n
December 5 Poncelet's Porism in Ellipses
December 3 Euclid I.43 Extended
November 28 Golden Ratio in an Irregular Pentagon
November 28 Golden Ratio in an Irregular Pentagon, Construction I
November 28 Golden Ratio in an Irregular Pentagon, Construction II
November 26 Sample Spaces and Random Variables
November 24 Lattice Multiplication
November 22 Long Multiplication
November 21 Egyptian Multiplication
November 19 Unfolding Spirals Illusion
November 18 What Is Probability?
November 13 Added a Gaelic word for centipede
November 12 Added a few variants to the 80-80-20 problem
November 11 A Sangaku with Many Circles and Some
November 1 Carpets in a Quadrilateral II
November 1 Two Arbelos, Two Chains
October 30 Archimedes' Twins in the Edo Period
October 30 Sangaku with 8 Circles
October 30 Reflections in Ellipse
October 29 Property of 6-Parpolygon
October 27 Conic Sections as Loci of Points
October 25 Optical Property of Ellipse
October 24 Al-Nayrizi's Construction
October 24 Euclid's Segment Division
October 24 Similar Right Triangles
October 23 7 = 2 + 5 Sangaku
October 23 Steiner's Sangaku
October 22 Twin Segments in Arbelos
October 22 Ellipse in Arbelos
October 21 Consecutive Isosceles Decomposition
October 20 Squares in Arbelos
October 19 6 Solutions to a derivative problem in the 80-80-20 triangle
October 17 2 Solutions to a modified problem in the 80-80-20 triangle
October 16 Pascal's Theorem, Homogeneous Coordinates
October 15 Three Incircles In a Right Triangle
October 12 Octagon in Parallelogram: Overlapping Regions
October 12 Octagon in Parallelogram
October 10 10 Solutions to the classical problem in the 80-80-20 triangle
October 9 Brianchon in Ellipse
October 9 Arithmetic Mean Sangaku II
October 8 What is so natural about “natural logarithms”?
October 8 The 80-80-20 Triangle
October 7 Euler’s formula for e
October 3 The 80-80-20 Triangle Problem, A Variant
October 3 2 is irrational, proof #14
October 2 Three Squares and Two Ellipses
October 1 N is irrational, proof #13
October 1 Chasles' Theorem, a Proof
September 30 Projective Proof of Pascal's Theorem
September 29 Illustration of Pascal's Theorem
September 25 Hjelmslev Theorem
September 24 Generalizing a Romanian Olympiad Problem
September 23 Four Incircles in Equilateral Triangle
September 21 Maximal Properties of the Pythagorean Relation
September 20 Pythagorean Condition in An Isosceles Right Triangle
September 18 Artisans vs Mathematicians
September 17 Approximate Construction of Regular Pentagon by A. Dürer
September 16 Construction of Regular Pentagon by H. W. Richmond
September 14 Regular Pentagon Construction by Y. Hirano
September 14 Pentagon Proportions Sangaku
September 13 Equilateral Triangle, Straight Line and Tangent Circles
September 11 Proof 75 of the Pythagorean Theorem
September 4 Circles in a Circular Segment
September 1 Steinhaus' Problem
August 30 Isotomy and Isogonality Hand-in-Hand
August 29 Lean Napoleon's Triangles
August 25 Reverse Spoke Illusion
August 25 Importance of Occluders: Motion Binding
August 25 Brick Wall Illusion
August 24 Occluded Wheel Illusion
August 22 Divergent Spirals Illusion
August 21 Rotating Top Illusion
August 20 White's Illusion, V-Variant
August 20 White's Illusion
August 19 Koffka's Illusion
August 14 Two Circles Inscribed in a Parallelogram
August 13 Eight Equal Tangents
August 12 Why 1/3 + 1/4 = 7/12?
August 12 Counting Chips On a Circle
August 11 Infinitude of Primes Via Coprime Pairs
August 10 Pythagorean Triples Calculator
August 9 Committee Chairs
August 8 Infinitude of Primes Via *-Sets
August 8 Infinitude of Primes Via Fermat Numbers
August 7 Langford and Skolem Sequences
August 4 Pythagorean Theorem by Hinged Dissection I
August 3 Proof #16 of the Butterfly Theorem
August 3 Two Triangles With Common Base and Altitude
August 2 Mirror Property of Altitudes via Pascal's Hexagram
July 24 Chameleons of Three Colors
July 19 Sangakus with a Mixtilinear Circle
July 18 cos(36°) = (1 + 5)/4
July 17 Area of Triangle
July 13 Pythagorean Theorem by Hinged Dissection II
July 12 Pythagorean Theorem by Hinged Dissection
July 11 Out of Pentagon Sangaku
July 10 Angle Trisection by Paul Vjecsner
July 9 Circles Lined on the Legs of a Right Triangle
July 9 Sequences of Touching Circles
July 8 Similar Triangles And More
July 8 Angle Bisectors On Circumcircle
July 8 Two Circles in a Square II
June 23 An Extension of van Schooten's Theorem
June 22 Relations in a Cyclic Polygon
June 22 Chasles' Theorem
June 21 Nine Squares
June 20 A Sangaku with an Egyptian Attachment
June 20 Sangaku with Versines
June 19 Harmonic Mean Sangaku
June 18 Abul Wafa al-Buzjani's Proof of the Pythagorean Theorem
June 17 Three Tangent Circles Sangaku
June 13 Arithmetic Mean Sangaku
June 12 Cyclic Hexagon
June 10 Make An Identity
June 6 Proof 5 of the Eyeball Theorem
June 1 Mirror Maze
May 28 Equilateral Triangles on Diagonals of Antiequilic Quadrilateral
May 26 Equilic Quadrilateral II
May 26 Equilic Quadrilateral I, A Variation
May 26 Equilic Quadrilateral I (a Flawed Proof)
May 25 Equilateral Triangles on Segments of Equilic Quadrilateral
May 24 Similar Triangles on Sides and Diagonals of a Quadrilateral
May 22 Full House
May 20 Circle Division by Euclid and Leonardo
May 19 Color Balls: a Game of Logic
May 18 Ways To Count
May 15 Signs and Sums in a Sequence
May 14 Product of Diagonals in Regular N-gon
May 13 A Relation in Triangle
May 11 Proof 12 of the irrationality of the square root of 2
May 10 Three Points on a Parabola
May 9 Greg Markowsky's Problem for Parabola
May 8 Proof #73 of the Pythagorean Theorem
May 7 Amoeba's Survival
May 6 Shortest Fence in a Quarter-Circle Pasture
May 5 Jumping Isn't Everything
May 4 3-Chain
May 4 Super Nim
May 4 Achieve the Equilibrium
May 4 Vector Addition and Subtraction
May 4 Caterpillar
May 4 Wolf and Rabbit
May 2 4 Travelers' Problem, Michel Cabart's Solution.
May 1 Sangaku Iterations, Is it Wasan?
April 30 The Erdös-Mordell Inequality
April 30 An Elementary Proof of Urquhart's Theorem
April 29 Lights Out
April 28 Mini Lights Out
April 27 Midline in Similar Triangles
April 17 Proof #15 of the Butterfly Theorem
April 13 Two Envelopes Paradox
April 12 Added a dynamic illustration to Archimedes' Lemma 9
April 10 Tower of Hanoi, the Hard Way
April 9 Thébault's Problem III, Proof
April 8 Y. Sawayama's Lemma
April 6 Parallel Chords II
March 29 Olof Hanner's Jigsaw Puzzle
March 20 Pythagorean Triples and Perfect Numbers
March 18 Butterflies in Quadrilaterals and Elsewhere
March 16 Napoleon's Theorem by Transformation
March 13 A brief introduction to Rational Trigonometry
March 12 Inaugurated the system for purchasing of individual applets
February 24 Hooper's Paradox
February 22 Square and Circle in a Gothic Cupola
February 20 Quadrilateral With Equal Opposite Sides And Angles
February 12 Started the No-ads Subscription
February 4 Update for the page of January 31
February 2 A Stronger Triangle Inequality
January 31 Equilateral Triangles and Incircles in a Square
January 29 Sangaku in a Square
January 28 Twenty five boys and twenty five girls around a table.
January 27 Six Balls, Two Weighings
January 18 Remarkable Line in a Quadrilateral
January 17 Two Circles in an Angle
January 6 Crossing Number of a Graph

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