Tag Archives: Geometry puzzles

Solution to Puzzle #134: Rotating Coins

Posted on April 3, 2016 by Alok Goyal

This was indeed a gem of a puzzle, and the more I have thought about it, the more I like it. Thanks again to Girish Tutakne for sharing this puzzle. I received a few correct answers – Suman Saraf, Prakhar … Continue reading →

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Puzzle #134: Rotating Coins

Posted on March 13, 2016 by Alok Goyal

This is a gem of a problem pointed to me by an avid puzzler and an IITD friend (now in Philippines) – Girish Tutakne. Thanks Girish. Even though I know the answer, it still baffles me! Suppose we have 2 … Continue reading →

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Solution to Puzzle #131: The Pyramid Problem

Posted on March 6, 2016 by Alok Goyal

This was a ver unintuitive problem, and thanks again to my nephew Karan Sharma on sending this problem. People who sent the correct answers included Abhinav Jain, Pratik Poddar and Suman Saraf. The answer is 5. It is kind of … Continue reading →

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Puzzle #131: The Pyramid Problem

Posted on February 21, 2016 by Alok Goyal

This is a beautiful geometry puzzle contributed by my nephew, Karan Sharma. The puzzle originally appeared in a PSAT exam in 1980, and was not really a “puzzle” until one student proved that there was a different answer than what … Continue reading →

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Solution to Puzzle #121: The Spider and the Fly

Posted on December 6, 2015 by Alok Goyal

This puzzle turned out to be more difficult than what I thought it was. There was only one correct answer – from Suman Saraf – very well done! The answer is 40 feet. There were a couple of people who … Continue reading →

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Puzzle #121: Spider and The Fly

Posted on November 10, 2015 by Alok Goyal

This is a puzzle whose variations many people would have done already. Yet, I found this to be very nice and not as simple as it may seem at first sight. I picked this from a Martin Garder book again … Continue reading →

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Solution to Puzzle #103: Proof Without Trigonometry

Posted on June 7, 2015 by Alok Goyal

A wonderful puzzle, and the solution is a beautiful one. This was a difficult one, and therefore I did not get as many answers to the puzzle. Abhinav was the first one to send a correct answer – and a … Continue reading →

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Puzzle #103: Proof Without Trigonometry

Posted on May 30, 2015 by Alok Goyal

This is a wonderful puzzle I found in the puzzle collection of The Guardian newspaper, the original source being Martin Gardner. The beauty of this puzzle is that one needs to use simple rules of geometry and we do not … Continue reading →

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Solution to Puzzle #101: Shortest Path Touching the X-axis

Posted on May 24, 2015 by Alok Goyal

Thanks to Arunima and Amol again for contributing a wonderful puzzle. This is a famous puzzle called the Heron’s Shortest Distance Problem and has historical roots. The puzzle can be solved through calculus, but can be solved without any calculus … Continue reading →

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Puzzle #101: Shortest Path Touching the X-Axis…

Posted on May 17, 2015 by Alok Goyal

This is a beautiful puzzle initially sent to me a month back by Arunima, a friend from IIT Delhi now in Washington DC. The same puzzle was sent to me by another friend’s son, Amol Aggarwal, now doing his PhD … Continue reading →

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