Abu Al-Wafa (940-998) established several trigonometric identities such as tan, sin, sec, and cosec. He made important innovations in spherical trigonometry, and his work on arithmetics for businessmen contains the first instance of using negative numbers in a medieval Islamic text. Doesn’t sound impressive, but without negative numbers and these trigonometric functions, higher level math is non-existent, and without higher level math, there would not be computers, smart phones, and many of the luxuries we take for granted.
