| 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 |
60o 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 |
