(c. 800

Baghdad Baghdad (; ar, بَغْدَاد , ) is the capital of Iraq and the second-largest city in the Arab world after Cairo. It is located on the Tigris near the ruins of the ancient city of Babylon and the Sassanid Persian capital of Ctesiphon. I ...

? – c. 860 Baghdad?) was a

geometer A geometer is a mathematician whose area of study is geometry. Some notable geometers and their main fields of work, chronologically listed, are: 1000 BCE to 1 BCE * Baudhayana (fl. c. 800 BC) – Euclidean geometry, geometric algebra * ...

who worked at the House of Wisdom in

and for in a short time in Damascus where he made astronomical observations. He was probably of

Iranian Iranian may refer to: * Iran, a sovereign state * Iranian peoples, the speakers of the Iranian languages. The term Iranic peoples is also used for this term to distinguish the pan ethnic term from Iranian, used for the people of Iran * Iranian lan ...

origin. His most important work was his ''Commentary on

Euclid's Elements The ''Elements'' ( grc, Στοιχεῖα ''Stoikheîa'') is a mathematical treatise consisting of 13 books attributed to the ancient Greek mathematician Euclid in Alexandria, Ptolemaic Egypt 300 BC. It is a collection of definitions, postulat ...

'' which contained nearly 50 additional

proposition In logic and linguistics, a proposition is the meaning of a declarative sentence. In philosophy, " meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same meaning. Equivalently, a proposition is the no ...

s and an attempted proof of the

parallel postulate In geometry, the parallel postulate, also called Euclid's fifth postulate because it is the fifth postulate in Euclid's ''Elements'', is a distinctive axiom in Euclidean geometry. It states that, in two-dimensional geometry: ''If a line segmen ...

. Described as having superb knowledge of Greek (quite unusual for a Muslim scholar), he is also credited with a translation of Shanaq al-Hindi's ''Book of Poisons'' from Pehlevi into

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

, ''Kitab al-Sumum''.

References

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External links

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* * 800s births 860 deaths People from Baghdad 9th-century Iranian mathematicians 9th-century mathematicians 9th-century people from the Abbasid Caliphate Mathematicians from the Abbasid Caliphate Astronomers from the Abbasid Caliphate Astronomers of the medieval Islamic world Middle Persian–Arabic translators 9th-century Arabic writers {{Iraq-scientist-stub