Representations of Trigonometric and Hyperbolic Functions in Terms of Sector Areas

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A sector of angle of a unit circle
has an area equal to
radians. So half the area can serve as the argument for the trigonometric functions via parametric equations for
and
. The two constructions shown are consistent with the trigonometric identities
and
. (As a consequence, circular functions are alternatively called trigonometric functions.)
Contributed by: S. M. Blinder (August 2011)
Open content licensed under CC BY-NC-SA
Snapshots
Details
The thumbnail and the third snapshot show the comparative behavior of corresponding trigonometric and hyperbolic functions.
Reference
[1] S. M. Blinder, Guide to Essential Math, Amsterdam: Elsevier Academic Press, 2008, pp. 71–72, 188–189.
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