**Thabit ibn Qurra** was an important Islamic mathematician who worked on number theory, astronomy and statics.

- This language was Thabit ibn Qurra's native language, but he was fluent in both Greek and Arabic.
- Some accounts say that Thabit was a money changer as a young man.
- In Baghdad Thabit received mathematical training and also training in medicine, which was common for scholars of that time.
- There Thabit's patron was the Caliph, al-Mu'tadid, one of the greatest of the 'Abbasid caliphs.
- At this time there were many patrons who employed talented scientists to translate Greek text into Arabic and Thabit, with his great skills in languages as well as great mathematical skills, translated and revised many of the important Greek works.
- There are, however, numerous manuscript versions of the third translation into Arabic which was made by Hunayn ibn Ishaq and revised by Thabit.
- Knowledge today of the complex story of the Arabic translations of Euclid's Elements indicates that all later Arabic versions develop from this revision by Thabit.
- However we must not think that the mathematicians such as Thabit were mere preservers of Greek knowledge.
- Far from it, Thabit was a brilliant scholar who made many important mathematical discoveries.
- In astronomy Thabit was one of the first reformers of the Ptolemaic system, and in mechanics he was a founder of statics.
- We shall examine in more detail Thabit's work in these areas, in particular his work in number theory on amicable numbers.
- In Book on the determination of amicable numbers Thabit claims that Pythagoras began the study of perfect and amicable numbers.
- Another important aspect of Thabit's work was his book on the composition of ratios.
- In this Thabit deals with arithmetical operations applied to ratios of geometrical quantities.
- Thabit generalised Pythagoras's theorem to an arbitrary triangle (as did Pappus).
- Thabit's work on parabolas and paraboliods is of particular importance since it is one of the steps taken towards the discovery of the integral calculus.
- An important consideration here is whether Thabit was familiar with the methods of Archimedes.
- Thabit also wrote on astronomy, writing Concerning the Motion of the Eighth Sphere.
- An important work Kitab fi'l-qarastun (The book on the beam balance) by Thabit is on mechanics.
- In this work Thabit proves the principle of equilibrium of levers.
- After giving a generalisation Thabit then considers the case of equally distributed continuous loads and finds the conditions for the equilibrium of a heavy beam.
- Finally we should comment on Thabit's work on philosophy and other topics.
- Thabit had a student Abu Musa Isa ibn Usayyid who was a Christian from Iraq.
- Thabit's concept of number follows that of Plato and he argues that numbers exist, whether someone knows them or not, and they are separate from numerable things.
- In other respects Thabit is critical of the ideas of Plato and Aristotle, particularly regarding motion.
- His son, Sinan ibn Thabit, and his grandson Ibrahim ibn Sinan ibn Thabit, both were eminent scholars who contributed to the development of mathematics.
- Neither, however, reached the mathematical heights of Thabit.

Born 836, Harran, Mesopotamia (now Turkey). Died 18 February 901, Baghdad, (now in Iraq).

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Ancient Arab, Ancient Greek, Astronomy, Origin Turkey, Number Theory, Special Numbers And Numerals

**Oâ€™Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive