An early Hindu work on astronomy, the*Surya Siddhanta*(ca. 400 A.D.), gives a table of half-chords based on Ptolemy's table (fig. 15). But the first work to refer explicitly to the sine as a function of an angle is the*Aryabhatiya*of Aryabhata (ca. 510), considered the earliest Hindu treatise on pure mathematics.¹ In this work Aryabhata (also known as Aryabhata the elder; born 475 or 476, died ca. 550)² uses the word*ardha-jya*for the half-chord, which he sometimes turns around to*jya–ardha*(“chord–half”); in due time he shortens it to*jya*or*jiva.*

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EP - 40 PB - Princeton University Press PY - 1998 SN - 9780691158204 SP - 35 T2 - Trigonometric Delights UR - http://www.jstor.org/stable/j.ctt1r2f46.10 Y2 - 2020/09/18/ ER -