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Paulo Ferro

@pauloferro.com

Math teacher and published author

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09.02.2026
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Latest posts by Paulo Ferro @pauloferro.com

Preview
Puzzle #4 The area of the isosceles triangle is 108. The dots separe the sides in equal parts. What is the area of the kite? Solution Let b and h be the base and the height of the isosceles triangle, respectโ€ฆ

Solution

08.03.2026 06:38 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
An isosceles triangle where the base is divided into two equal parts by a dot and the two equal sides are divided into three equal parts by two dots. A green kite is inside the triangle where the top vertex coincides with the vertex of the triangle and the other vertices are the two top dots of the equal sides and the dot in the base of the triangle.

An isosceles triangle where the base is divided into two equal parts by a dot and the two equal sides are divided into three equal parts by two dots. A green kite is inside the triangle where the top vertex coincides with the vertex of the triangle and the other vertices are the two top dots of the equal sides and the dot in the base of the triangle.

Puzzle #4

The area of the isosceles triangle is 108. The dots separe the sides in equal parts.

What is the area of the kite?

Check the solution in the comments.

#math #geometry #puzzle #mathsky

08.03.2026 06:37 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(9/9) A warning: these puzzles can lead to a serious puzzle addiction! Enjoy the challenge!

You can pre-order it on Amazon or any bookstore around the World. There are paperback, hardcover and Kindle versions available.

03.03.2026 08:04 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0

(8/9) All the puzzles have step-by-step solutions. The puzzles can be solved by geometry puzzle lovers of all ages. The puzzler does not need to be an ace in geometry to solve them.

03.03.2026 08:04 ๐Ÿ‘ 1 ๐Ÿ” 1 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(7/9) The information given to solve the puzzle should be as minimal as possible, sometimes to the point that the reader might think that it is not possible to solve it. This is part of the challenge of puzzles.

03.03.2026 08:04 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(6/9) Puzzles should not only be fun in their design, but they should also be fun to solve. Their shape should be appealing to arouse curiosity in the reader.

03.03.2026 08:04 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(5/9) The first chapter, Solving a Puzzle, offers a typical puzzle, which then is solved step-by-step. It presents how geometry is used to solve it, and the logical thinking leading to the solution.

03.03.2026 08:04 ๐Ÿ‘ 1 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(4/9) There are three types of geometry puzzles in this book:

โ€ข No shape-based puzzles, i.e., triangles, circles, etc.

โ€ข General shape-based puzzles, i.e., a hamburger, a bird, etc.

โ€ข Japanese shape-based puzzles, i.e., a samurai, a bonsai, etc.

03.03.2026 08:04 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(3/9) Even if mathematical puzzles are new to the reader, this book is a great place to start. Puzzle solving is not only fun; it will also enhance the reader's understanding of mathematics. More experienced puzzlers will also find very challenging opportunities.

03.03.2026 08:04 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

(2/9) This book will challenge mathematical skills in a totally different way from the usual geometric puzzles. These 120 puzzles are visually intriguing. Mastering Geometry Puzzles has 5 chapters of puzzles, each one corresponding to a level of difficulty, from the very easy to the very hard.

03.03.2026 08:04 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Cover of the book Mastering Geometry Puzzles.

Cover of the book Mastering Geometry Puzzles.

Back cover of the book Mastering Geometry Puzzles.

Back cover of the book Mastering Geometry Puzzles.

(1/9) My new book ๐Œ๐š๐ฌ๐ญ๐ž๐ซ๐ข๐ง๐  ๐†๐ž๐จ๐ฆ๐ž๐ญ๐ซ๐ฒ ๐๐ฎ๐ณ๐ณ๐ฅ๐ž๐ฌ will be released on April 9, 2026.

You can pre-order it on Amazon ๐Ÿ‘‡
www.amazon.com/Mastering-Ge...

Learn more about it in the comments.

#math #geometry #puzzle #book #MasteringGeometryPuzzles #booksky

03.03.2026 08:04 ๐Ÿ‘ 7 ๐Ÿ” 2 ๐Ÿ’ฌ 2 ๐Ÿ“Œ 1
Preview
Puzzle #3 The figure is created out of twelve matchsticks. Modify the position of four matchsticks to get two squares. Solution

Solution

01.03.2026 06:13 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
A big square divided into four congruent small squares made with twelve matchsticks.

A big square divided into four congruent small squares made with twelve matchsticks.

Puzzle #3

The figure is created out of twelve matchsticks.

Modify the position of four matchsticks to get two squares.

Check the solution in the comments.

#math #matchstick #puzzle #mathsky

01.03.2026 06:11 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 3 ๐Ÿ“Œ 0
Preview
Puzzle #2 The number 403 is created out of fifteen matchsticks. Modify the position of two matchsticks to get a number divisible by 9. This puzzle was published on The New York Times and on The Guardian. Solโ€ฆ

Solution

22.02.2026 07:16 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0
The number four hundred three made with fifteen matchsticks.

The number four hundred three made with fifteen matchsticks.

Puzzle #2

The number 403 is created out of fifteen matchsticks.

Modify the position of two matchsticks to get a number divisible by 9.

This puzzle was published on @nytimes.com and on @theguardian.com.

Check the solution in the comments.

#math #matchstick #puzzle #mathsky

22.02.2026 07:16 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
The title of the book, Mastering Geometry Puzzles, is in the top. In the middle, inside a circle, it is written one hundred twenty geometry puzzles and five levels of difficulty. Its release date, April 9, 2026, is in the bottom center.

The title of the book, Mastering Geometry Puzzles, is in the top. In the middle, inside a circle, it is written one hundred twenty geometry puzzles and five levels of difficulty. Its release date, April 9, 2026, is in the bottom center.

My new book ๐Œ๐š๐ฌ๐ญ๐ž๐ซ๐ข๐ง๐  ๐†๐ž๐จ๐ฆ๐ž๐ญ๐ซ๐ฒ ๐๐ฎ๐ณ๐ณ๐ฅ๐ž๐ฌ will be released on April 9, 2026.

The book contains 120 geometry puzzles divided into 5 difficulty levels, from the very easy to the very hard. Each puzzle has a step-by-step solution.

#math #geometry #puzzle #book #MasteringGeometryPuzzles #mathsky #booksky

17.02.2026 17:21 ๐Ÿ‘ 3 ๐Ÿ” 1 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0

It is a link to my blog where you can find the solution.

16.02.2026 10:42 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Preview
Puzzle #1 The isosceles trapezoid/trapezium is composed of seven matchsticks. Modify the position of three matchsticks to get two equilateral triangles. This puzzle was published on NCTM and on The Guardian.โ€ฆ

Solution

15.02.2026 11:02 ๐Ÿ‘ 0 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
Trapezoid/trapezium made with seven matchsticks.

Trapezoid/trapezium made with seven matchsticks.

Puzzle #1

The isosceles trapezoid/trapezium is composed of seven matchsticks.

Modify the position of three matchsticks to get two equilateral triangles.

This puzzle was published on @nctm.org and on @theguardian.com.

Check the solution in the comments.

#math #matchstick #puzzle #mathsky

15.02.2026 11:02 ๐Ÿ‘ 2 ๐Ÿ” 0 ๐Ÿ’ฌ 1 ๐Ÿ“Œ 0
The title of the book, Mastering Geometry Puzzles, is in the center. Its release date, April 9, 2026, is in the bottom center.

The title of the book, Mastering Geometry Puzzles, is in the center. Its release date, April 9, 2026, is in the bottom center.

My new book ๐Œ๐š๐ฌ๐ญ๐ž๐ซ๐ข๐ง๐  ๐†๐ž๐จ๐ฆ๐ž๐ญ๐ซ๐ฒ ๐๐ฎ๐ณ๐ณ๐ฅ๐ž๐ฌ will be released on April 9, 2026.

Pre-orders will begin on March 19, 2026.

Stay tuned for more news about it soon.

#math #geometry #puzzle #book #MasteringGeometryPuzzles #mathsky #booksky

09.02.2026 10:43 ๐Ÿ‘ 8 ๐Ÿ” 0 ๐Ÿ’ฌ 0 ๐Ÿ“Œ 0