Hyperbolic Trigonometry
A variation of trigonometry.
Hyperbolic trig functions are defined using ex and e–x.
The six hyperbolic trig functions relate to each other in ways
that are similar to conventional trig
functions. Hyperbolic trig
plays an important role when trig functions have imaginary or complex
arguments.
Note: Hyperbolic trigonometry has no relation
whatsoever to hyperbolic geometry.

See also
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