Abul Wafa Buzjani, a Persian astronomer born in about 940 in Buzhgan, (now Torbat-e Jam) in Iran, had in 959 moved to Iraq, where he has studied mathematics and worked principally in the field of trigonometry.

He has written a number of books, most of which no longer exist; also studying the movements of the moon.

The crater Abul Wáfa on the Moon is named after him.

He has devised a wall quadrant for the accurate astronomy measurement of the declination of stars.

He has also introduced the tangent function and improved methods of calculating trigonometry tables and developed novel ways of solving some problems of spherical triangles.

He has established various trigonometric identities and discovered the law of sines for spherical triangles.