On spherical trigonometry in the medieval near east and in Europe

AbstractThis article analyzes several medieval trigonometric treatises including The Book on Unknown Arcs of a Sphere by the Spanish-Arabic mathematician al-Jayyani (11th century); De triangulis by the German scholar Regiomontanus, or Johannes Müller (15th century); and writings of several Oriental scholars devoted to the same subject. It is conjectured that The Book on Unknown Arcs of a Sphere was one of the Islamic sources of the trigonometric treatise by Regiomontanus