Mathematics in Ancient and Medieval India c8.7

c8.7

( 1 ) *Trigonometical functions* :—In India, like Babylon and Greece, the study of the properties of the right-angled triangle inscribed in a circle in connection with the use of gnomon in astronomical measurement was given much importance. The circle was divided into quadrants and circumference into many equal parts. Three functions² *Jyā*, *Kojyā* and *Utkramajyā* were used in the development of this new geometry, known as plane trigonometry. The modern equivalents of these functions (Fig. 18) are as follows :—