jan 1, 975 - Al-Batani
Description:
Al-Batani extends the Indian concepts of sine and cosine to other trigonometric ratios, like tangent, secant and their inverse functions. By the end of the 10th century trigonometry occupied an important place in astronomy texts with chapters on sines, chords, tangents and cotangents, and the formulae for spherical calculations.Added to timeline:
Date:
jan 1, 975
Now
~ 1051 years ago