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Equidecomposition of a Rectangle and a Square: What is this about?
A Mathematical Droodle


This applet requires Sun's Java VM 2 which your browser may perceive as a popup. Which it is not. If you want to see the applet work, visit Sun's website at http://www.java.com/en/download/index.jsp, download and install Java VM and enjoy the applet.


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What if applet does not run?

Explanation

Copyright © 1996-2010 Alexander Bogomolny

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The applet purports to illustrate a simple fact:

  A rectangle can be cut into several pieces which, after translation and rotation, combine into a square of equal area.

The applet only demonstrates this fact for sufficiently elongated rectangle. Rectangles that are nearer a square to start with can be cut into strips that combine into rectangles of the sort the applet handles well, i.e., in which the length is at least twice its width.

Since every triangle is equidecomposable with a rectangle, we can also claim that every triangle is equidecomposable with a square! An even more obvious conclusion is that two rectangles of equal area are equidecomposable. This fact can be established directly and likely in a more economical manner.

(The problem of constructing a square equal in area to a given rectangle has been solved by Euclid's Elements II.14.)

References

  1. G. Frederickson, Dissections: Plane & Fancy, Cambridge University Press, 1997, p. 222

Equidecomposition by Dissection

  1. Carpet With a Hole
  2. Equidecomposition of a Rectangle and a Square
  3. Equidecomposition of Two Parallelograms
  4. Equidecomposition of Two Rectangles
  5. Equidecomposition of a Triangle and a Rectangle
  6. Equidecomposition of a Triangle and a Rectangle II
  7. Perigal's Proof of the Pythagorean Theorem
  8. Two Symmetric Triangles Are Directly Equidecomposable
  9. Wallace-Bolyai-Gerwien Theorem

Copyright © 1996-2010 Alexander Bogomolny

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