# Math Monday: Mathematical Coffee Table

By George Hart for the Museum of Mathematics

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

### 21 Responses to Math Monday: Mathematical Coffee Table

1. I like the giant spider on the underside

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

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

4. I smell a re-make!

5. 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. I love this!

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

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

11.  I want!! Love it!

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

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

17. Anonymous on said:

Run, fellow spider. RUUUUUUN!

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