around 850

### Ibn Qurra's Pythagorean Theorem Proofs

Pythagorean theorem proofs by dissection

Arab polymath Thābit ibn Qurra revised an earlier translation of the* Elements* and translated several other Greek works from the times of Euclid to Ptolemy. He also produced two original proofs of the Pythagorean theorem as well a generalization of the theorem (which, while valid, was stated without proof).

Thābit ibn Qurra presented two original proofs of the Pythagorean theorem using a method of dissection which he called the method of reduction to triangles and rearrangement by juxtaposition. These proofs appeared in a letter to a friend written around around 850 CE and are preserved in the library of the Hagia Sophia Museum in Istanbul, Turkey.