Did you know some math problems were used to discriminate against groups of people? This is one such problem, and it stumped me! But it has an unbelievably elegant solution. Take any equilateral triangle and pick a random point inside the triangle. Draw from each vertex a line to the random point. Two of the three angles at the random point are known, let’s say angles x and y. If the 3 line segments from each vertex to the random point were removed out of the original triangle to form a new triangle, what would the new triangle’s angles be?
Thanks to Daniel E for sharing this puzzle! Also do check out these sources for the historical background to this problem and other similar “killer problems” that are easy to state and nearly impossible to solve unless you know the trick (in which case they are readily solvable problems).
My blog post for this video:
Sources and historical background
Gold Plated Goof video on “coffin problems” – Simple Math Problems To Fool The Best. The triangle problem is the third problem presented (around 5:33)
Tanya Khovanova, and Alexey Radul. “Jewish Problems.”
Originally published as: Tanya Khovanova, and Alexey Radul. “Killer Problems.” The American Mathematical Monthly, vol. 119, no. 10, 2012, pp. 815–823. JSTOR, JSTOR, www.jstor.org/stable/10.4169/amer.math.monthly.119.10.815.
If you like my videos, you can support me at Patreon:
Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you.
My Blog: https://mindyourdecisions.com/blog/
Newsletter (sent only for big news, like a new book release): http://eepurl.com/KvS0r
If you buy from the links below I may receive a commission for sales. This has no effect on the price for you.
“The Joy of Game Theory” shows how you can use math to out-think your competition. (rated 3.8/5 stars on 31 reviews)
“The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias” is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 5/5 stars on 2 reviews)
“Math Puzzles Volume 1” features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews.
“Math Puzzles Volume 2” is a sequel book with more great problems. (rated 5/5 stars on 3 reviews)
“Math Puzzles Volume 3” is the third in the series. (rated 3.8/5 stars on 4 reviews)
“40 Paradoxes in Logic, Probability, and Game Theory” contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews)
“The Best Mental Math Tricks” teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 4 reviews)
“Multiply Numbers By Drawing Lines” This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 3 reviews)