The Rsines of any two arcs of a circle are reciprocally multiplied by their Rcosines; the products are then divided by the radius; the sum of the quotients is equal to the Rsine of the sum of the two arcs, and their difference is the Rsine of the difference of the arcs.

Bhaskara II (1150) (Siddhantashiromani Goladhyaya, Jyotpatti 21 and 22):चापयोरिष्टयोर्दोर्ज्ये मिथः कोटिज््यकाहते।त्रिज््ययाभक्ते तयोरै क््ययं तच््चचापैक््यस््य दोर््ज््यका॥चापान््तरस््य जीवा स््ययात्तयोरन््तरसंमिता।अन््यज््ययासाधने सम््यगियं ज््ययाभावनोदिता॥

Datta, Bibhutibhushan, and Avadesh Narayan Singh.———. ‘Hindu Trigonometry’ (revised by K.S. Shukla). Indian Journal of History of Science 18 (1) (1983): pp. 39-108. quoted from Bhaskar Kamble, The Imperishable Seed: How Hindu Mathematics Changed the World and why this History was Erased, Garuda Prakashan Private Limited, 2022 ISBN 9798885750189