What is the Connection Between \(\theta\) and Trigonometric Function Outputs?

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SUMMARY

The discussion centers on the relationship between the angle \(\theta\) and the outputs of trigonometric functions, specifically sine, cosine, and tangent. Participants highlight that calculators utilize Taylor expansions for these computations, while also referencing historical methods such as Ptolemy's trigonometric tables. The conversation explores whether there exists a direct algebraic manipulation linking \(\theta\) to its trigonometric ratios, particularly before the advent of calculus. The inquiry emphasizes the need for understanding both historical and mathematical contexts of trigonometric calculations.

PREREQUISITES
  • Understanding of trigonometric functions, specifically sine, cosine, and tangent.
  • Familiarity with Taylor and Maclaurin series expansions.
  • Knowledge of historical mathematical methods, including Ptolemy's trigonometric tables.
  • Basic algebraic manipulation skills related to angles and ratios.
NEXT STEPS
  • Research the derivation and applications of Taylor series for trigonometric functions.
  • Explore historical methods of calculating trigonometric values, including Ptolemy's contributions.
  • Learn about the geometric interpretations of trigonometric ratios in right triangles.
  • Investigate algebraic techniques for approximating trigonometric values without calculus.
USEFUL FOR

Mathematicians, educators, students studying trigonometry, and anyone interested in the historical development of mathematical concepts related to angles and trigonometric functions.

brendan_foo
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I believe that calculators use Taylor expansions to compute sines, cosines and tan's based upon the argument [itex]\theta[/itex] (in radians of course). However, my question is, aside from these expansions, is there some sort of link between [itex]\theta[/itex] and the output of the function itself.

I mean I know that [itex]\cos{\theta} = \frac {adj}{hyp}[/itex] and the other trig ratios, but was this just worked out by hand, pencil and paper and kept in a tabular form before the Taylor expansion was devised? Is there a direct link between [itex](\frac{adj}{hyp})[/itex] and [itex]\theta[/itex].

Get me?!
 
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Trig values were, yes, worked out by hand ()

One of Ptolemy's major contributions to Greek maths was his trig tables.
The Indian mathematicians did the same, but independently of the Greeks.

EDIT:
Hmm..now that I reread your question, it seems you were after something else..
 
No that's a great answer.. just curious. I know the Maclaurin series for trig functions takes the parameter and manipulates it to get a solution. However I wanted to know if there was some other relation between the argument and the answer. Say I had the angle [itex]\frac{\pi}{9}[/itex] and I wanted to know the cosine of it, that is the ratio of the adjacent to the hypotenuse, then was there some algebraic manipulation you could do with the value [itex]\frac{\pi}{9}[/itex] to yield the solution.

Aside from doing it by hand, I was curious whether it could be done another way before the days of calculus.
 

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