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By George Hart for the Museum of Mathematics

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If you make a coffee table that express a mathematical idea and place it right in the middle of your living room, that certainly makes a statement to all who visit that math is central in your life.

This looks like an ordinary square coffee table, but note the cuts and the three hinges.

The table instantly transforms into an equilateral triangle, which is handy if you don’t know how many people are coming over.

This bottom view shows the structure. The seven legs are positioned to support it in each corner, in both the square and triangle configuration. Greg Fredrickson describes how Jan de Koning constructed it for Joop Van Der Vaart, based on a suggestion of Howard Eves, that derives from the original 1903 dissection of Henry Dudeny.

More:
See all of George Hart’s Math Monday columns

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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Comments

  1. Mike Boyd says:

    I like the giant spider on the underside :)

  2. Susan Jones says:

    Only problem: too many sharp corners ! I love math, but I also love my shins.

  3. NursesLabs says:

    Very educational…
    Just how many shapes can you make with this?

  4. andrew says:

    I smell a re-make!

  5. Avi Baron says:

    Here is a clean image of the cuts you’d have to make for this.
    http://www.johnrausch.com/PuzzlingWorld/images/fig021.gif

  6. Dudeney, as the Wikipedia link clearly points not Dudeny.

  7. LOL I SEE A DADDY LONG-LEGS ON THE BOTTOM!

  8. is that a spider on the bottom of the table?

  9. That Dam Kat says:

    What a fabulous design! Going to visit the Museum of Mathematics now : )

  10. Orla says:

     I want!! :) Love it! 

  11. You’ve inspired me, Next project coming right up.

  12. that spider….makes me dislike the whole table. 

  13. that spider….makes me dislike the whole table. 

  14. that spider….makes me dislike the whole table. 

  15. that spider….makes me dislike the whole table. 

  16. Anonymous says:

    Run, fellow spider. RUUUUUUN!

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