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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

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor for Boing Boing and WINK Books. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.


  • http://www.facebook.com/profile.php?id=1517809393 Mike Boyd

    I like the giant spider on the underside :)

  • http://profiles.google.com/siouxgeonz Susan Jones

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

  • http://www.nurseslabs.com NursesLabs

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

  • http://amhou.wordpress.com/ andrew

    I smell a re-make!

  • http://twitter.com/AIBaron Avi Baron

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

  • http://www.mostlymaths.net/ Ruben Berenguel

    Dudeney, as the Wikipedia link clearly points not Dudeny.

  • http://profiles.google.com/tom.molyn Thomas Molyneux

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

  • http://www.facebook.com/profile.php?id=712115840 Shawn Connally

    I love this!

  • http://www.facebook.com/kelseyharrell Kelsey R Harrell

    is that a spider on the bottom of the table?

  • http://twitter.com/ThatDamKat That Dam Kat

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

  • http://twitter.com/orlacummins Orla

     I want!! :) Love it! 

  • http://www.facebook.com/people/Evan-ALexander-Judson/1356541105 Evan ALexander Judson

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

  • http://www.facebook.com/SPANKEEZ Shelbie Corral

    that spider….makes me dislike the whole table. 

  • http://www.facebook.com/SPANKEEZ Shelbie Corral

    that spider….makes me dislike the whole table. 

  • http://www.facebook.com/SPANKEEZ Shelbie Corral

    that spider….makes me dislike the whole table. 

  • http://www.facebook.com/SPANKEEZ Shelbie Corral

    that spider….makes me dislike the whole table. 

  • Anonymous

    Run, fellow spider. RUUUUUUN!

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