Mathematician:Nasir al-Din al-Tusi

In Persian:  نصیر الدین طوسی , known in the west as Tusi.

Full name:  محمد بن محمد بن الحسن طوسی  - Khawaja Muhammad ibn Muhammad ibn Hasan Tūsī.

Multi-discipline scientist and prolific writer who pre-empted several later Western scientists:
 * Darwin with his ideas on evolution
 * Copernicus on his heliocentric view of the solar system
 * Galileo with his insight into the nature of the Milky Way.

The first to separate the science of trigonometry, particularly spherical trigonometry, from that of astronomy.

Nationality
Persian

History

 * Born: 18 Feb 1201, Tus, Khorasan (now Iran)
 * Died: 26 June 1274, Kadhimain (near Baghdad, now in Iraq)

Theorems and Definitions

 * Law of Sines
 * Law of Sines for Spherical Triangles
 * Law of Tangents for Spherical Triangles


 * Tusi Couple

Books and Papers
Around 150 works, including:


 * 1272: Zij-i Ilkhani (Ilkhanic Tables): a major astronomical treatise


 * Kitāb al-Shakl al-Qattā (Book on the Complete Quadrilateral): a five volume summary of trigonometry
 * Al-Tadhkirah fi'ilm al-Hay'ah (A memoir on the Science of Astronomy)
 * Akhlaq-i-Nasri: a work on ethics, in which he described his Theory of Evolution
 * Al-Risalah al-Asturlabiyah (A Treatise on the Astrolabe)
 * Sharh al-Isharat (Commentary on Avicenna's Isharat)
 * Awsaf al-Ashraf: a short mystical-ethical work in Persian
 * Tajrīd al-iʿtiqād (Summation of Belief): a commentary on Shia doctrines

Also see

 * : Chapter $5$: Eternal Triangles