On a proof of Thabit ibn Qurra’s Generalization of the Pythagorean theorem.

One of the most interesting generalizations of the Pythagorean theorem was stated by Thabit in the IX century. However, as claimed an expert of history of math- ematics the Arab mathematician did not present the proof, as it can likely be obtained by elementary properties regarding similar triangles. According to historical documents, it is challenging to establish whether a proof of Tha ̄bit’s theorem exists based exclusively on equidecomposibility, as in the case of the Pythagorean and Pappus theorems. This article presents the corresponding proof