who is known as the father of trigonometry
Hipparchus Hipparchus of Nicaea' (/hɪˈpɑːrkəs/; Greek: Ἵππαρχος, Hipparkhos; c. 190 – c. 120 BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry[1] but is most famous for his incidental discovery of precession of the equinoxes.[2]