Dec 29 |
A Warmup Inequality from Vasile Cirtoaje |

Dec 28 |
Van Aubel's Theorem for Quadrilaterals and Generalization |

Dec 28 |
A Cyclic Inequality on [-1,1] |

Dec 27 |
Red And Green Balls in Red And Green Boxes |

Dec 27 |
Quadratic Inequalities on [-1,1] |

Dec 26 |
An Integral Identity with Two Functions |

Dec 26 |
Black Boxes in a Chain |

Dec 25 |
A Problem with Three Equilateral Triangles |

Dec 25 |
A Cyclic Inequality from India In Three Variables And More |

Dec 24 |
A Plane Filling Curve for the Year 2017 |

Dec 23 |
Square Root of 2 is Irrational, Proof 29 |

Dec 23 |
An Equilateral Triangle In Parallel Lines |

Dec 21 |
A Problem in a Special Tangential Quadrilateral |

Dec 20 |
An Easy Cyclic Inequality And a Remark |

Dec 18 |
Two Chickens in Bigger Boxes |

Dec 17 |
Two Chickens in Boxes |

Dec 17 |
Chickens in Boxes |

Dec 16 |
Equilateral Triangle from Equilateral Triangle |

Dec 16 |
Quotient Estimates II |

Dec 16 |
Finding the Circumradius of the Excentral Triangle |

Dec 16 |
Problem 1 from the 2006 IMO |

Dec 15 |
Problem 4160 from the Crux Mathematicorum |

Dec 15 |
A Theorem of M. Mansion |

Dec 15 |
A Property of Incenter Relative to Circumcircle |

Dec 14 |
Quotient Estimates |

Dec 12 |
Problem 2 from the 2017 Canada MO |

Dec 11 |
Problem 1 from the 2017 Canada MO |

Dec 10 |
Dorin Marghidanu's Permuted Inequality |

Dec 9 |
A Cyclic Inequality In Three Variables by Sorin Radulescu |

Dec 8 |
Waiting for Multiple Heads |

Dec 7 |
Concerning Even Number of Heads |

Dec 6 |
A Limit With Sums, Roots, And Binomial Coefficients |

Dec 5 |
Two-Sided Inequality by Dorin Marghidanu |

Dec 4 |
A Trigonometric Observation in Right Triangle |

Dec 4 |
Double Sums by Dorin Marghidanu |

Dec 1 |
Probability with Factorials |

Nov 30 |
Pythagorean Theorem through a Rearrangement of a Parallelogram |

Nov 30 |
Problem M317 from Crux Mathematicorum |

Nov 30 |
Problem 790 from Pentagon: an Inequality in Two Variables |

Nov 29 |
Varignon's Theorem, Proof Without Words |

Nov 29 |
A Memorable Fact |

Nov 28 |
Pythagorean Theorem Through Three Right Isosceles Triangles |

Nov 28 |
A Rectangle in Three Circles by Hirotaka Ebisui |

Nov 27 |
Problem 4142 From Crux Mathematicorum |

Nov 26 |
Integer Chord in a Polynomial Graph |

Nov 26 |
Rolling a Die |

Nov 26 |
Loaded Dice II |

Nov 25 |
Points on a Square Grid |

Nov 25 |
Problem A-6 from the 1992 Putnam Math Competition |

Nov 25 |
Problem A-2 from the 2002 Putnam Math Competition |

Nov 24 |
The Averages of Sides and Angles in a Triangle |

Nov 23 |
Kunihiko Chikaya's Inequality with Parameter |

Nov 23 |
Random Intervals with One Dominant |

Nov 23 |
An Integral Estimate |

Nov 22 |
Birds on a Wire. Solution by Bogdan Lataianu |

Nov 21 |
Overlapping Random Intervals |

Nov 20 |
An Inequality in Triangle XI |

Nov 20 |
A Mathematical Gallery |

Nov 20 |
Simple Construction of the Circle of Apollonius |

Nov 20 |
An Area Inequality in Right Triangle |

Nov 19 |
Problem 4186 from Crux Mathematicorum |

Nov 18 |
Probability of Four Random Integers Having a Common Factor |

Nov 17 |
An Inequality between AM, QM and GM |

Nov 17 |
An inequality in 2+2 variables from SSMA magazine |

Nov 16 |
Dorin Marghidanu's Cyclic Inequality in Three Variables III |

Nov 16 |
Exploring Vecten's Wreaths with Linear Algebra |

Nov 16 |
Equilateral triangle and squares |

Nov 15 |
Two Problems by Kunihiko Chikaya |

Nov 14 |
Three Random Points on a Circle |

Nov 14 |
Semicircle Coverage |

Nov 14 |
Hemisphere Coverage |

Nov 12 |
Samuel G. Walters' Congruence |

Nov 10 |
Problem 4117 from Crux Mathematicorum |

Nov 10 |
Without Definitions: Why $\displaystyle\frac{1}{3}+\frac{2}{5}=\frac{11}{15}?$ |

Nov 10 |
A Followup on Lewis Carroll's Pillow Problem |

Nov 9 |
Practical Inevitability of Empty Spaces |

Nov 8 |
Practical Inevitability of Clustering |

Nov 7 |
Impossiblity Condition in Concurrent Cevians |

Nov 1 |
A Cyclic Inequality in Three Variables by Uche E. Okeke |

Oct 31 |
A Problem in Division of Polynomials |

Oct 30 |
A Property of Product of Special Matrices, Probably Folklore |

Oct 30 |
Collinearity in Tangent Circles |

Oct 30 |
Tying Knots In Brazil |

Oct 30 |
Trigonometric Inequality with Integrals |

Oct 28 |
Coin Tossing Contest |

Oct 28 |
Probability of $2^n$ Beginning with Digit $1$ |

Oct 27 |
Recollecting Forgotten Digit |

Oct 27 |
Three Variables, Three Constraints, Two Inequalities (Only One to Prove) - by Leo Giugiuc |

Oct 27 |
A Cyclic Inequality from Math Phenomenon |

Oct 26 |
Numbers in a Square |

Oct 26 |
Numbered Balls Out Of a Box |

Oct 26 |
Balls of Two Colors II |

Oct 25 |
Odds and Chances in Horse Race Betting |

Oct 24 |
A Cyclic Inequality from the 6th IMO, 1964 |

Oct 24 |
An Inequality of Degree 3 with Inradius |

Oct 23 |
Waiting for an Ace |

Oct 23 |
A Long Cyclic Inequality of Degree 4 |

Oct 22 |
Chess tournament with 1.5 Points Winners |

Oct 20 |
A Not Quite Cyclic Inequality from Tibet |

Oct 20 |
Probability a la Tristram Shandy |

Oct 20 |
Dan Sitaru's Cyclic Inequality in Four Variables |

Oct 18 |
Leo Giugiuc's Cyclic Quickie in Four Variables |

Oct 18 |
Problem 11984 From the American Mathematical Monthly |

Oct 17 |
A Cyclic Inequality with Powers 2 through 7 |

Oct 16 |
A pizza with a hole |

Oct 16 |
A Cyclic Inequality With Constraint in Two Triples of Variables |

Oct 16 |
Probability of Visiting Grandparents |

Oct 15 |
Simulating Probabilities |

Oct 14 |
An Inequality with Integrals |

Oct 14 |
Average Visibility of Moviegoers |

Oct 13 |
Probability of a Cube Ending with 11 |

Oct 13 |
An Inequality in Triangle with a Constraint |

Oct 13 |
A Limit of a Series of Determinants |

Oct 12 |
An Unusual Problem by Leo Giugiuc |

Oct 12 |
Determinants in $\mathbb{Z}_2$ |

Oct 11 |
Problem 6 from Dan Sitaru's Algebraic Phenomenon |

Oct 11 |
Loaded Dice |

Oct 10 |
Six Numbers, Three Inequalities |

Oct 9 |
Six Numbers, Two Inequalities |

Oct 9 |
Six Numbers, One Inequality |

Oct 9 |
Problem 1 from the Ninth Nordic Mathematical Contest (1994) |

Oct 8 |
An Identity in Cyclic Quadrilateral |

Oct 7 |
Dan Sitaru's Sum of a Series |

Oct 6 |
Emil Stoyanov's From Reflections to Altitudes |

Oct 2 |
An Inequality with Constraint in Four Variables VI |

Oct 1 |
Dorin Marghidanu's Two-Sided Inequality |

Sep 29 |
3-4-5, Golden Ratio |

Sep 29 |
Kunihiko Chikaya's Inequality |

Sep 27 |
Long Huynh Huu's Inequality and Solution |

Sep 27 |
A Simplified Version of Leo Giugiuc's Inequality from the AMM |

Sep 27 |
An Inequality with Exponents |

Sep 26 |
Determinants in Pascal's Triangle |

Sep 25 |
Dan Sitaru's Cyclic Inequality with a Constraint and Cube Roots II |

Sep 24 |
Dorin Marghidanu's Inequality in Many Variables Plus Two More |

Sep 24 |
Carpets in Right Triangle |

Sep 23 |
Cyclic Inequality with Arctangents |

Sep 23 |
Square, 45 Degrees Angle and Pythagoras' Look-alike |

Sep 22 |
An Inequality with the Most Important Cevians |

Sep 21 |
Dan Sitaru's Cyclic Inequality with a Constraint and Cube Roots |

Sep 20 |
Dan Sitaru's Cyclic Inequality in Three Variables VI |

Sep 20 |
Further Arithmetic Progression in 30-60-90 Triangle |

Sep 20 |
Dorin Marghidanu's Inequality with Radicals |

Sep 19 |
An Equation in RxR from Romania |

Sep 19 |
The Contest Corner Problem 210 from Crux |

Sep 18 |
An Inequality with Determinants VII |

Sep 17 |
Marian Dinca's Inequality |

Sep 16 |
Hung Viet's Inequality IV |

Sep 16 |
Parallels through the Vertices of Equilateral Triangle |

Sep 14 |
Dorin Marghidanu's Inequality in Many Variables |

Sep 13 |
A Cyclic Inequality in Three Variables XXV |

Sep 13 |
Dan Sitaru's Cyclic Inequality in Three Variables IV |

Sep 11 |
Problem 4165 from Crux Mathematicorum |

Sep 8 |
Problem #6 from the Italian MO 2000 |

Sep 4 |
An Inequality with Constraint XX |

Sep 3 |
An Inequality with Constraint XIX |

Sep 1 |
An Inequality with Constraint XVIII |

Sep 1 |
An Inequality with Two Sets of Cevians |

Aug 31 |
All Trigonometric Inequality in Triangle |

Aug 29 |
Problem 4002 from Crux Mathematicorum |

Aug 28 |
Two Solution: One Correct, One Illuminating. An Example |

Aug 26 |
An Inequality in Triangle with Side Lengths and Circumradius |

Aug 26 |
Problem CC156 From Crux Mathematicorum |

Aug 21 |
A Problem in Pentagon with Supplementary Angles |

Aug 19 |
Problem 4132 from Crux Mathematicorum |

Aug 19 |
A Problem That Fermat Might Have Liked |

Aug 19 |
A Problem in Pentagon with Right Angles |

Aug 17 |
Stan Fulger's Observation in Right Triangle |

Aug 16 |
Surprising Length Dependence In Equilateral Triangle by Miguel Ochoa Sanchez |

Aug 15 |
Problem 4033 from Crux Mathematicorum |

Aug 15 |
An Inequality with Just Two Variable And an Integer |

Aug 10 |
Asymmetric Propeller, the XXI Century |

Aug 9 |
Dan Sitaru's Exercise with Pi and Ln |

Aug 9 |
A Refinement of Turkevich's Inequality |

Aug 8 |
Cyclic Inequality in Three Variables by Marian Cucoanes |

Aug 8 |
Playing on Flanks |

Aug 8 |
Leo Giugiuc's Inequality in Triangle, Solely with Cotangents |

Aug 7 |
An Inequality in Triangle, with Sides and Medians III |

Aug 7 |
An Integral from the RMM |

Aug 6 |
Mickey Might Be a Red Herring in the Mickey Mouse Theorem |

Aug 5 |
An Inequality with Two Pairs of Triplets |

Aug 4 |
Simple Yet Uncommon Inequalities with Absolute Value |

Aug 4 |
A Problem From the Romanian Mathematical Competitions (2016) |

Aug 4 |
Seyran Ibrahimov's Inequality |

Aug 2 |
An Inequality with Sides, Cosines, and Semiperimeter |

Aug 2 |
The Very First Functional Equation at IMO |

Aug 2 |
An Inequality from the 1967 IMO Shortlist |

Aug 1 |
Adil Abdulayev's Inequality With Angles, Medians, Inradius and Circumradius |

Aug 1 |
Leuenberger's Inequality for Medians, Inradius and Circumradius |

Aug 1 |
A Problem from the 1967 IMO Shortlist |

Jul 31 |
Inequality 101 from the Cyclic Inequalities Marathon |

Jul 31 |
Moments in a Peculiar Cyclic Polygon |

Jul 28 |
Problem 2 from the 2017 IMO |

Jul 28 |
An Inequality with Exradii and an Altitude |

Jul 27 |
A Problem from the 1985 Balkan Mathematical Olympiad (Shortlist) |

Jul 26 |
Van Khea's Quickie |

Jul 26 |
One More Property of Equilateral Triangles |

Jul 26 |
The Lepidoptera of the Triangle |

Jul 25 |
60^{o} Angle And Importance of Being The Other End of a Diameter |

Jul 24 |
Michael Rozenberg's Inequality in Three Variables with Constraints |

Jul 23 |
Problem 11867 from the American Mathematical Monthly |

Jul 22 |
An Inequality with Inradius and Side Lengths |

Jul 20 |
Geometric/Trigonometric Observation/Exercise |

Jul 20 |
An Inequality in Two Or More Variables II |

Jul 20 |
Problem From the 2016 IMO Shortlist |

Jul 19 |
Trigonometry by Watching |

Jul 18 |
Golden Ratio In Three Circles And Common Secant |

Jul 18 |
Refinement on Dan Sitaru's Cyclic Inequality In Three Variables |

Jul 17 |
Sladjan Stankovik's Inequality In Four Variables |

Jul 16 |
Small Triangle from Small Triangle |

Jul 15 |
Dan Sitaru's Cyclic Inequality In Three Variables with Constraints IV |

Jul 13 |
Leo Giugiuc's Inequality with Constraint |

Jul 13 |
Dan Sitaru's Cyclic Inequality in Three Variables III |

Jul 12 |
An Inequality with Inradius and Excenters |

Jul 12 |
An Inequality with Arbitrary Roots |

Jul 11 |
Cyclic Quadrilateral, Angle Bisector And Isosceles Triangle |

Jul 11 |
Dorin Marghidanu's Inequality in Complex Plane |

Jul 11 |
Leo Giugiuc's Optimization with Constraint |

Jul 11 |
An Inequality with Sines But Not in a Triangle |

Jul 10 |
Dan Sitaru's Cyclic Inequality in Three Variables II |

Jul 8 |
Dan Sitaru's Inequality: From Three Variables to Many in Two Ways |

Jul 7 |
A Not Quite Cyclic Inequality |

Jul 6 |
An Inequality in Integers III |

Jul 5 |
An Inequality in Two Or More Variables |

Jul 4 |
Dan Sitaru's Cyclic Inequality In Three Variables |

Jul 4 |
An Inequality with Complex Numbers of Unit Length II |

Jul 3 |
An Unsolvable Riccati Equation |

Jul 2 |
Dan Sitaru's Inequality with Three Related Integrals and Derivatives |

Jul 1 |
An Inequality from a Vietnamese Problem Book |

Jul 1 |
Wonderful Trigonometry In Equilateral Triangle |

Jun 30 |
Dorin Marghidanu's Inequality with Generalization |

Jun 29 |
Same Integral, Three Intervals |

Jun 28 |
An Inequality with Cotangents And the Circumradius |

Jun 27 |
$x_n=\sin 1+\sin 3+\sin 5+\cdots+\sin (2n-1)$ |

Jun 26 |
Another Property of Number 4 |

Jun 25 |
An Inequality with Constraint in Four Variables V |

Jun 24 |
Four Integrals in One Inequality |

Jun 24 |
Dorin Marghidanu's Light Elegance in Four Variables |

Jun 23 |
A Cyclic Inequality in Three or More Variables |

Jun 22 |
A Limit with Fractions, Roots, Powers and Series |

Jun 22 |
Probability of Degenerate Random Matrix in Z(2) |

Jun 20 |
An Inequality with Angles and Integers |

Jun 20 |
An Inequality with Cyclic Sums on Both Sides III |

Jun 19 |
Dan Sitaru's Cyclic Inequality In Three Variables with Constraints III |

Jun 19 |
Dorin Marghidanu's Spanish Problem |

Jun 19 |
The 2016 ARML Competition, Problem 7 |

Jun 18 |
An Identity in Triangle with a 135 Degrees Angle |

Jun 17 |
A Cyclic Inequality in Three Variables XXV |

Jun 17 |
Nagel Point and Centroid on Adjacent Isosceles Triangles |

Jun 15 |
Nagel Point on the Incircle in Isosceles Triangle |

Jun 15 |
Centroid on the Incircle in Isosceles Triangle |

Jun 15 |
The Range of r/R in Triangle with Centroid on the Incircle |

Jun 14 |
Centroid on the Incircle in Right Triangle |

Jun 13 |
An Inequality with Powers And Logarithm |

Jun 13 |
Distances to Three Points on a Circle |

Jun 12 |
An Equation in Factorials |

Jun 12 |
Problem 4 from the 2016 OBJM TST |

Jun 12 |
An Inequality Solved by Changing Appearances |

Jun 8 |
Michael Rozenberg's Inequality in Two Variables |

Jun 7 |
An Inequality for Cevians And The Ratio of Circumradius and Inradius |

Jun 7 |
A Problem with a Magical Solution from Secrets in Inequalities |

Jun 6 |
Gheorghe Stoica's Problem from Gazeta Matematica |

Jun 6 |
The Midpoint of an Angle Bisector - a Problem by A. A. Zaslavsky |

Jun 5 |
Parallel Lines in Rhombus |

Jun 5 |
A Cyclic Inequality of Degree Four |

Jun 5 |
Two Circles, Two Segments - One Ratio |

Jun 4 |
An Inequality in Fractions with Absolute Values |

Jun 4 |
R and r When G on Incircle |

Jun 3 |
Problem 4 from the 4th BJMO Team Selection Test |

Jun 3 |
Two Regular Pentagons Joined at Vertex |

Jun 2 |
Another Inequality with Logarithms, But Not Really |

Jun 1 |
Segment Trisection II |

May 31 |
An Inequality with Cyclic Sums on Both Sides II |

May 31 |
Leo Giuguic's Exercise |

May 30 |
A Problem of Two Incircles by Miguel Ochoa Sanchez |

May 29 |
Refinement of Padoa's Inequality |

May 28 |
Two Butterfly Theorems by Sidney Kung |

May 28 |
A Cyclic Inequality in Triangle for Integer Powers |

May 27 |
J. Arioni's Proof of Morley's Theorem |

May 27 |
Mixing Incenter And Orthocenter in Greece |

May 27 |
Dan Sitaru's Amazing, Never Ending Inequality |

May 26 |
Dorin Marghidanu's Tribute to Descartes |

May 26 |
An Inequality for Sides and Area |

May 25 |
A Problem from Greece via Peru |

May 25 |
Dan Sitaru's Cyclic Inequality In Three Variables with Constraints II |

May 24 |
An Inequality with Angle Trisectors |

May 23 |
A System of Two Equations Replete with Squares |

May 23 |
An Inequality of the Areas of Triangles Formed by Circumcenter And Orthocenter |

May 22 |
An Old Inequality |

May 22 |
A Cyclic Inequality in Three Variables with a Variable Hierarchy |

May 22 |
Minimum of a Cyclic Sum with Logarithms |

May 21 |
Inequalities with Double And Triple Integrals |

May 21 |
Why The Number of Primes Could Not Be Finite? |

May 20 |
An Inequality with Cyclic Sums on Both Sides |

May 20 |
Golden Ratio in Wu Xing |

May 19 |
Optimization with Many Variables |

May 19 |
A Problem from the Danubius-XI Contest |

May 18 |
An Inequality in Four Weighted Variables |

May 18 |
An Inequality in Three (Or Is It Two) Variables |

May 18 |
Equilateral Triangle in Square And the Pedal Circle of Its Apex |

May 18 |
Equilateral Triangle in Square with the Cevians through Its Apex |

May 17 |
A Simple Solution to a Difficult Sangaku Problem |

May 17 |
Dan Sitaru's Integral Inequality with Powers of a Function |

May 17 |
Equilateral Triangle in Square and Its Circumcircle |

May 5 |
Dan Sitaru's Inequality by Induction |

May 5 |
Golden Ratio in Three Regular Pentagons II |

May 4 |
An Inequality with Constraint in Four Variables IV |

May 4 |
An Inequality with Two Cyclic Sums |

May 3 |
Dorin Marghidanu's Inequality with Constraint |

May 3 |
Golden Ratio in Three Regular Pentagons |

May 3 |
From Perpendicular Center Lines to Concyclic Points |

May 3 |
An Inequality with Sides, Altitudes, Angle Bisectors and Medians |

May 2 |
Construction: Parallel Line through Point |

May 1 |
More of More of Gloden Ratio in Equilateral Triangles |

Apr 30 |
Cubes Constrained |

Apr 30 |
An Inequality with Tangents and Sides |

Apr 30 |
From Six Variables to Four - It's All the Same |

Apr 29 |
An Inequality With Six Variables and Constraints |

Apr 29 |
Excircles in Trapezoid |

Apr 28 |
A Partly Cyclic Inequality in Four Variables |

Apr 28 |
(tan(72)$\pm$tan( 60)sin(30$\mp$18)= 1 |

Apr 28 |
Functions And Triangles |

Apr 27 |
Three Travelers in Uniform Motion |

Apr 26 |
Geometric Proof of Hlawka's Inequality |

Apr 26 |
A Simple Cyclic Inequality in Three Variables |

Apr 25 |
An Inequality with One Tangent and Six Sines |

Apr 24 |
Concurrence in Right Triangle |

Apr 23 |
Simple Inequality with a Variety of Solutions |

Apr 22 |
Hlawka-like Inequality for Convex Functions |

Apr 21 |
A Cyclic Inequality in Three Variables XXIV |

Apr 21 |
Bottema's Point Sibling |

Apr 20 |
Twin Inequalities in Four Variables: Twin 1 |

Apr 20 |
Twin Inequalities in Four Variables: Twin 2 |

Apr 19 |
Dorin Marghidanu's Inequality in Integer Variables |

Apr 19 |
K. Knop's Problem with Two Regular Pentagons And an Equilateral Triangle |

Apr 18 |
Similar Parallelograms on Sides of a Triangle |

Apr 18 |
Unsolved Problem from Crux Solved |

Apr 16 |
An Inequality with Integrals and Radicals |

Apr 16 |
An inequality with Three Points |

Apr 14 |
An inequality with Cosines and a Sine |

Apr 14 |
Problem 3 from the EGMO2017 |

Apr 13 |
A Cyclic Inequality in Three Variables XXIII |

Apr 13 |
An Inequality with Circumradii And Distances to the Vertices |

Apr 12 |
A simple integral, III |

Apr 12 |
Problem 1 from the EGMO2017 |

Apr 11 |
An Inequality with Just Two Variable VIII |

Apr 11 |
Cyclic Inequality with Square Roots And Absolute Values |

Apr 10 |
Klamkin's Quickie via Peru Geometrico |

Apr 10 |
Cyclic Inequality with Square Roots |

Apr 9 |
Fun Identity in Right Triangle |

Apr 9 |
An Inequality with a Parameter and a Constraint |

Apr 9 |
Golden Ratio in an Isosceles Trapezoid with a 60 degrees Angle II |

Apr 8 |
A Problem with Two Similar Rectangles |

Apr 8 |
Cultivating Regular Pentagons |

Apr 5 |
Problem 4010 from Crux Mathematicorum |

Apr 3 |
How Do Angle Trisectors Divide the Area? |

Apr 1 |
Gireaux's Theorem |

Apr 1 |
The Law of Cosines and the Law of Sines Are Equivalent |

Mar 31 |
Another Problem from the 2016 Danubius Contest |

Mar 31 |
Concurrent Chords in a Circle, Equally Inclined |

Mar 30 |
Dorin Marghidanu's Inequality with Maximum Side |

Mar 29 |
Inequality with Constraint from Dan Sitaru's Math Phenomenon |

Mar 28 |
Proofs of Schweitzer's inequality |

Mar 27 |
Dan Sitaru's Inequality with Tangents II |

Mar 26 |
Problem 4 From the 2016 Pan-African Math Olympiad |

Mar 26 |
Triangle Area in Square with Incircle |

Mar 26 |
A Cyclic But Not Symmetric Inequality in Four Variables |

Mar 25 |
Applications of Schweitzer's Inequality |

Mar 24 |
An Inequality with Cyclic Sums And Products |

Mar 24 |
Sitaru-Schweitzer Inequality |

Mar 23 |
Rotating Square in Search of the Golden Ratio |

Mar 23 |
A Problem From a Mongolian Olympiad for Grade 11 |

Mar 23 |
Hung Viet's Inequality III |

Mar 22 |
An Inequality in Triangle with Sides and Medians II |

Mar 22 |
Inequality with Two Variables? Think Again |

Mar 21 |
Minimum under Two Constraints |

Mar 21 |
Small Change Makes Big Difference |

Mar 20 |
Darij Grinberg's Inequality In Three Variables |

Mar 18 |
Imad Zak's Cyclic Inequality in Three Variables II |

Mar 18 |
Dan Sitaru's Cyclic Inequality In Three Variables with Constraints |

Mar 18 |
The power of substitution III: proving an inequality with two variables |

Mar 18 |
Imad Zak's Cyclic Inequality in Three Variables |

Mar 18 |
Dorin Marghidanu's Cyclic Inequality in Three Variables II |

Mar 17 |
A Case for Determinants |

Mar 15 |
An Inequality with Areas, Norms, and Complex Numbers |

Mar 15 |
An Inequality with a Variety of Circumradii |

Mar 14 |
An Inequality in Triangle, with Sides and Sums |

Mar 11 |
Homothety in Three Tangent Circles II |

Mar 11 |
Homothety in Three Tangent Circles |

Mar 10 |
An Inequality in Triangle, with Sines II |

Mar 9 |
Pentagon And Decagon, Both Regular |

Mar 8 |
A Cyclic Inequality in Three Variables XXII |

Mar 8 |
Angle Bisector in Square |

Mar 8 |
Hung Viet's Inequality II |

Mar 7 |
Regular Pentagon Construction by K. Knop |

Mar 7 |
An Inequality with Just Two Variable VII |

Mar 7 |
Tangent to Circle in Three Steps |

Mar 6 |
A Cyclic Inequality in Three Variables XXI |

Mar 6 |
An Angle in Square Conjoint with Regular Pentagon |

Mar 5 |
A Cyclic Inequality in Three Variables XX |

Mar 4 |
An Acyclic Inequality in Three Variables |

Mar 3 |
An Inequality with Just Two Variables VI |

Mar 3 |
An Inequality in Triangle, with Sines |

Mar 2 |
A Cyclic Inequality in Three Variables XIX |

Mar 2 |
An Inequality in Triangle, with Integrals |

Mar 2 |
Jordan and Kober Inequalities, PWW |

Mar 2 |
Star, Six Pentagons and Golden Ratio |

Mar 2 |
Graphing Equations Is Useful, V |

Mar 1 |
General Butterfly in Pictures |

Feb 28 |
An Identity with Inradius and Circumradii |

Feb 27 |
An Inequality with Just Two Variables V |

Feb 26 |
A Cyclic Inequality in Three Variables XVIII |

Feb 26 |
Pairing Monotone and Convex Functions |

Feb 26 |
FJG Capitan's Sangaku |

Feb 25 |
An Inequality In Triangle and Without II |

Feb 25 |
A Cyclic Inequality in Three Variables XVII |

Feb 25 |
The Beauty of Fractions |

Feb 23 |
Tony Foster's Proof of Viviani's Theorem |

Feb 22 |
Problem 4096 from Crux Mathematicorum |

Feb 22 |
An Inequality with Constraint XVII |

Feb 22 |
Dorin Marghidanu's Example II |

Feb 21 |
An Inequality with Inradius and Circumradii |

Feb 21 |
An Inequality Not in Triangle |

Feb 19 |
Problem 4087 from Crux Mathematicorum |

Feb 18 |
Cubic Optimization with Partly Linear Constraints |

Feb 17 |
Le Khanh Sy's Problem |

Feb 17 |
A Cyclic Inequality in Three Variables XVI |

Feb 16 |
An Inequality with Complex Numbers of Unit Length |

Feb 16 |
An Inequality in Triangle with Differences of the Medians |

Feb 15 |
An Inequality in Triangle with the Circumradius, Inradius and Angle Bisectors |

Feb 15 |
An Inequality in Triangle with the Sines of Half-Angles and Cube Roots |

Feb 15 |
Cubic Optimization with Linear Constraints |

Feb 14 |
A Cyclic Inequality with Many Sums |

Feb 13 |
An Inequality In Triangle with Sines of Half-Angles |

Feb 13 |
An Inequality in Triangle with Medians, Sides and Circumradius |

Feb 13 |
Dorin Marghidanu's Cyclic Inequality with Constraint |

Feb 13 |
Orthic Triangle in a Triangle with a 120 degrees angle |

Feb 12 |
A Cyclic Inequality in Three Variables And One More |

Feb 11 |
An Inequality with Just Two Variables IV |

Feb 11 |
Emil Stoyanov's New Year's Problem, a Sequel |

Feb 9 |
An Inequality In Triangle and Without |

Feb 9 |
An Inequality with Fractions |

Feb 8 |
A Triangle With a 45 Degrees Angle in Square |

Feb 8 |
Dorin Marghidanu's Cyclic Inequality in Three Variables |

Feb 8 |
Golden Ratio in a Mutually Beneficial Relationship |

Feb 7 |
Weitzenbock by Sanchez |

Feb 6 |
An Inequality on Circumscribed Quadrilateral |

Feb 6 |
Stathis Koutras' Butterfly |

Feb 6 |
Igor Sharygin's Problem in Circumscribed Quadrilateral |

Feb 6 |
Dan Sitaru's Cyclic Inequality In Many Variables |

Feb 4 |
A Cyclic Inequality in Three Variables XV |

Feb 3 |
An Inequality with Constraint in Four Variables III |

Feb 3 |
Dan Sitaru's Cyclic Inequality In One Variable |

Feb 3 |
Leo Giugiuc's Inequality for the Medians |

Feb 2 |
Inequalities with Constraint XV and XVI |

Feb 2 |
Cyclic Inequality with Logarithms |

Feb 1 |
An Inequality with Altitudes and Angle Bisectors |

Feb 1 |
An Inequality with Altitudes and Medians |

Jan 31 |
Constrained Inequality with Reciprocals |

Jan 30 |
Divergence of the Harmonic Series (Details) |

Jan 30 |
Converse Construction in Pompeiu's Theorem |

Jan 29 |
Excircle in Equilateral Triangle |

Jan 28 |
Problem 2, the 36th IMO (1995) |

Jan 28 |
An Application of Cauchy-Schwarz Inequality |

Jan 27 |
Tran Hoang Nam's Cyclic Inequality in Three Variables |

Jan 27 |
Early Refinement of the Ionescu-Weitzenbock Inequality |

Jan 26 |
Problem in a Special Trapezoid |

Jan 26 |
Daniel Dan's Optimization in Three Variables |

Jan 26 |
Stathis Koutras' Theorem II |

Jan 26 |
Padoa's Inequality |

Jan 25 |
An Inequality in Triangle with Altitudes, Medians And Symmedians |

Jan 24 |
Leo Giugiuc's Cyclic Inequality in Three Variables |

Jan 24 |
An Inequality with Just Two Variable III |

Jan 23 |
Area Inequality in Three Triangles |

Jan 22 |
Parallel Lines in a Quadrilateral II |

Jan 21 |
An Inequality in Triangle, Mostly with the Medians |

Jan 20 |
Hung Nguyen Viet's Inequality with Radicals and Chebyshev |

Jan 19 |
Question That Changes with Time |

Jan 18 |
Sladjan Stankovik's Inequality With Constraint II |

Jan 18 |
An Inequality in Triangle and In General |

Jan 17 |
Getting Ahead by Two Points |

Jan 17 |
Radicals, Radicals, And More Radicals in an Inequality |

Jan 16 |
Find Minimum without Calculus |

Jan 16 |
A Cyclic Inequality in Three Variables XIV |

Jan 16 |
Isosceles Triangle with Two Points on Base |

Jan 14 |
Angle Chasing in a 75-30-75 triangle |

Jan 14 |
Nine Point Center in Square |

Jan 14 |
An Inequality for the Cevians through Spieker Point via Brocard Angle |

Jan 13 |
Optimization in Four Variables with Two Constraints |

Jan 11 |
An Inequality in Reciprocals III |

Jan 10 |
An Inequality with Determinants VI |

Jan 10 |
A Cyclic Inequality in Three Variables XIII |

Jan 10 |
An Inequality with Constraint XIV |

Jan 9 |
An Exercise without Calculating Aids |

Jan 8 |
A Special Triangle with a Line Through the Lemoine Point |

Jan 8 |
A Case of Divergence |

Jan 8 |
One Inequality - Two Domains |

Jan 7 |
Marian Cucoanes' Inequality With Roots and Powers |

Jan 7 |
A Triple Integral Inequality |

Jan 6 |
A Cyclic Inequality in Three Variables XII |

Jan 6 |
Brocard Point and a Relation of Circumradii |

Jan 6 |
Integrals of a Function And Its Inverse |

Jan 6 |
Adil Abdullayev's Inequality With Roots and Powers |

Jan 6 |
A Cyclic Inequality in Three Variables XI |

Jan 5 |
An Inequality with Constraint in Four Variables II |

Jan 5 |
An Inequality with Powers of Six |

Jan 4 |
Algebraic-Geometric Inequality |

Jan 4 |
A Cyclic Inequality in Three Variables X |

Jan 3 |
From Angle Bisector to 120 degrees Angle |

Jan 3 |
From The Sum of Angles To The Sum of Sines |

Jan 2 |
Average Distance to N Points |

Jan 2 |
A Cyclic Inequality in Three Variables IX |

Jan 2 |
A Cyclic Inequality in Three Variables VIII |

Jan 1 |
Emil Stoyanov's New Year's Problem |