Questions tagged [trigonometry]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
1
vote
1answer
66 views

Establishment of relation between angles and sides of a triangle

I was looking for an historical approach to learn about the initiation of trigonometry but got stuck in a part where I have been trying to undestand but couldn't till now. By far, I could learn that ...
0
votes
1answer
132 views

Etymology of 'sine'. The Arabic 'jayb' and 'jiba' derive from the Sanskrit 'jivā' ... but why not from the more common Sanskrit 'jyā'?

The Indian word for what we call sine was 'jyā'. The Surya-siddhanta mentions 'jyā' many many times. As does the Aryabhatiya. In contrast they mention the synonym 'jivā' only once or twice. So why was ...
3
votes
1answer
85 views

Origin of "Inverse Pythagorean Theorem"

There is a lot of information on the history of the Pythagorean theorem, but not much on its closely related cousin; the Inverse Pythagorean Theorem. Would appreciate any resources on the the history ...
1
vote
3answers
227 views

Why do we still use degrees and cycles if we all implicitly use radians in trigonometric functions?

For various reasons already discussed in other stackexchange posts, we implicitly use radians in trigonometric functions by convention. For example, one period of $sin(x)$ lies in $0 \leq x < 2\pi$,...
4
votes
0answers
47 views

Where could I find the reference for the statement of Euler finding out the coefficients of Fourier series?

I am reading Carlslaw's "Introduction to the Theory of Fourier's Series and Integrals", first chapter on the history of Fourier series, page 3. The author asserts that Clairaut and Euler did ...
6
votes
1answer
120 views

When did trigonometry start using negative numbers?

I'm asking this question looking at the unit circle, and thinking that greek mathematicians didn't use negative numbers. Maybe that can give enough insight into what I'm asking?