Trigonometry as an independent discipline and Tusi couple
Trigonometría como disciplina independiente y par de al-Tusi
- Date
- c. 1250 · confidence medium
- Place
- Maragheh, Persia (Iran)
- Credited to
- Nasir al-Din al-Tusi
- People
- 👤 Nasir al-Din al-Tusi1201–1273
- Field
- Knowledge & symbols
What was discovered
The Treatise on the Complete Quadrilateral systematises plane and spherical trigonometry (the law of sines, solving triangles) as separate from astronomy; it introduces the Tusi couple, which generates rectilinear motion from two circular ones.
Copernicus used the Tusi couple without citing the source; the route of transmission is still debated.
What it led to
- Regiomontanus's trigonometry
- Copernicus's models
- kinematic geometry
Built on
- Ptolemaic geocentric model (Almagest)c. 150
- Abu al-Wafa (tangents and the law of sines)
Made possible
- Ilkhanic astronomical tables
- navigation