Where does sine come from?
Date: 6 Jan 1995 12:23:18 -0500 From: Patty Wu Subject: (none) Dear Dr. Math, Hi! I'm a student from Internet, and I'm doing a reserch on Ask Dr. Math. What I need to do is to ask a question to Dr. Math, and get a response. So could you please answer my question? That would help me a lot. Thanks in advance. The question is - Who is the inventor of Sin? And when did he/she discover it? Also, how did he/she do it?
Date: 6 Jan 1995 17:29:10 -0500 From: Anonymous Subject: Re: Origin of Sine Hi Patty! According to my Math History book ("A History of Mathematics," by Carl Boyer), the concept of the sine came from India. The first mention of it that we know of is in a series of books called the Siddhantas, literally "Systems" (of astronomy). They were written around the year 400, supposedly by Surya, the Sun god. Already, Greek Mathematicians had studied the relationship between the lengths of chords of a circle and the angles of the circle that they cross. What is significant about what was done in India is that they started looking at the relationships between half-chords and the halves of the angle that the whole chord would cross. Draw the chord of a circle and the angle of the circle that it crosses, and then bisect both--can you see why the relationship between the half-chord and the half-angle is the Sine? Through a mistranslation from Arabic to Latin, somehow the Indian word for this relationship, jiva, became our word sine. Later, in the 1700s, through the work of the mathematician Euler, sine came to mean a ratio, not merely the length of a certain line. I hope this helps! Elizabeth, a math doctor
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.