# A Proof Without Words of the Pythagorean Theorem

This proof I found in R. Nelsen's sequel *Proofs Without Words* II. (It's due to Poo-sung Park and was originally published in *Mathematics Magazine*, Dec 1999). Starting with one of the sides of a right triangle, construct 4 congruent right isosceles triangles with hypotenuses of any subsequent two perpendicular and apices away from the given triangle. The hypotenuse of the first of these triangles (in red in the diagram) should coincide with one of the sides.

What if applet does not run? |

### References

- R. B. Nelsen,
*Proofs Without Words II*, MAA, 2000

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