TRIG(X) VS X
Put the mouse pointer on the point on the circle, left-click, drag and observe ...
Note that here the "angle" is measured in radians, i.e. it is the length of the pink arc.
The ("half-chord") is the historical root of the word "sine":
See Earliest known uses of words in mathematics:
The Hindus had given the name jiva to the half chord in trigonometry, and the Arabs had taken this over as jiba. In the Arabic language there is also a word jaib meaning "bay" or "inlet." When Robert of Chester came to translate the technical word jiba, he seems to have confused this with the word jaib (perhaps because vowels were omitted); hence he used the word sinus, the Latin word for "bay" or "inlet."
This applet also shows the meaning of the word "tangent"!
Lets repeat: the length of the pink arc can also be expressed as speedxtime, i.e. wt, then we have a relationship between t and trig(wt).
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