Abū ʿAbd Allāh Muḥammad ibn Muʿādh al-Jayyānī ( ar, أبو عبد الله محمد بن معاذ الجياني; 989,
Cordova,
Al-Andalus – 1079,
Jaén,
Al-Andalus) was an
Arab,
mathematician,
Islamic scholar, and
Qadi from
Al-Andalus (in present-day Spain). Al-Jayyānī wrote important commentaries on
Euclid's ''
Elements
Element or elements may refer to:
Science
* Chemical element, a pure substance of one type of atom
* Heating element, a device that generates heat by electrical resistance
* Orbital elements, parameters required to identify a specific orbit of ...
'' and he wrote the first known treatise on
spherical trigonometry.
Life
Little is known about his life. Confusion exists over the identity of ''al-Jayyānī'' of the same name mentioned by
ibn Bashkuwal (died 1183),
Qur'anic scholar, Arabic
Philologist, and expert in
inheritance laws (farāʾiḍī). It is unknown whether they are the same person.
''The book of unknown arcs of a sphere''
Al-Jayyānī wrote ''The book of unknown arcs of a sphere'', which is considered "the first treatise on
spherical trigonometry",
although spherical trigonometry in its ancient Hellenistic form was dealt with by earlier mathematicians such as
Menelaus of Alexandria
Menelaus of Alexandria (; grc-gre, Μενέλαος ὁ Ἀλεξανδρεύς, ''Menelaos ho Alexandreus''; c. 70 – 140 CE) was a Greek Encyclopædia Britannica "Greek mathematician and astronomer who first conceived and defined a sphe ...
, who developed
Menelaus' theorem to deal with spherical problems. However,
E. S. Kennedy points out that while it was possible in pre-Islamic mathematics to compute the magnitudes of a spherical figure, in principle, by use of the table of chords and Menelaus' theorem, the application of the theorem to spherical problems was very difficult in practice.
[ ( cf. , in )] Al-Jayyānī's work on spherical trigonometry "contains formulae for
right-handed triangles, the general
law of sines, and the solution of a
spherical triangle by means of the polar
triangle." This treatise later had a "strong influence on European mathematics", and his "definition of
ratios as numbers" and "method of solving a spherical triangle when all sides are unknown" are likely to have influenced
Regiomontanus.
See also
*
List of Arab scientists and scholars
*
Islamic mathematics
Mathematics during the Golden Age of Islam, especially during the 9th and 10th centuries, was built on Greek mathematics (Euclid, Archimedes, Apollonius) and Indian mathematics (Aryabhata, Brahmagupta). Important progress was made, such as full ...
Notes
References
*
PDF version
*
*
989 births
1079 deaths
Astronomers of Al-Andalus
Mathematicians of Al-Andalus
11th-century mathematicians
11th-century Al-Andalus people
Scientists who worked on qibla determination
Mathematicians who worked on Islamic inheritance
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