Abū al-Wafā' al-Būzjānī

Abul Wafa al-Buzjani (Arabic: ابوالوفا البوزجانی) , extended name: transl|ar|ALA|Abū al-Wafāʾ Muḥammad ibn Muḥammad ibn Yaḥyā ibn Ismāʿīl ibn al-ʿAbbās al-Būzjānī (Arabic: ابوالوفا محمد بن محمد بن یحیی بن اسماعیل بن العباس البوزجانی) (born 10 June 940 - died 1 July 998) [http://www.encyclopaediaislamica.com/madkhal2.php?sid=2053] was a Persian mathematician and astronomer. He was born in Buzhgan, (now Torbat-e Jam) in Iran.

In 959 AD, he moved to Iraq. He studied mathematics and worked principally in the field of trigonometry. He wrote a number of books, most of which no longer exist. He also studied the movements of the moon. The Abul Wáfa crater on the moon is named for him.

Astronomy

He devised a wall quadrant for the accurate astronomy measurement of the declination of stars. He also introduced the tangent function and improved methods of calculating trigonometry tables and developed novel ways of solving some problems of spherical triangles.

Mathematics

He established the trigonometric identities:

:$sin(a\; +\; b)\; =\; sin(a)\; cos(b)\; +\; cos(a)\; sin(b)$:$cos(2\; a)\; =\; 1\; -\; 2sin^2(a)$:$sin(2\; a)\; =\; 2sin(a)\; cos(a)$

and discovered the sine formula for spherical geometry (which looks similar to the law of sines):

:$frac\{sin(A)\}\{sin(a)\}\; =\; frac\{sin(B)\}\{sin(b)\}\; =\; frac\{sin(C)\}\{sin(c)\}$

ee also

*List of Iranian scientists

Further reading

* cite encyclopedia
last = Youschkevitch
first = A.P.
title = Abul Wafa al-Buzjani, Muhammad Ibn Muhammad Ibn Yahya Ibn Ismail Ibn Al-Abbas
encyclopedia = Dictionary of Scientific Biography
volume = 1
pages = 39-43
publisher = Charles Scribner's Sons
location = New York
date = 1970
isbn = 0684101149
*

References