# hyperbolic function

- a function of an angle expressed as a relationship between the distances from a point on a hyperbola to the origin and to the coordinate axes, as hyperbolic sine or hyperbolic cosine: often expressed as combinations of exponential functions.

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## Origin of hyperbolic function

First recorded in 1885–90

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

## hyperbolic function

- any of a group of functions of an angle expressed as a relationship between the distances of a point on a hyperbola to the origin and to the coordinate axes. The group includes sinh (hyperbolic sine), cosh (hyperbolic cosine), tanh (hyperbolic tangent), sech (hyperbolic secant), cosech (hyperbolic cosecant), and coth (hyperbolic cotangent)

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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## hyperbolic function

[hī′pər-bŏl′ĭk]

- Any of a set of six functions related, for a real or complex variable x, to the hyperbola in a manner analogous to the relationship of the trigonometric functions to a circle, including:
- The hyperbolic sine, defined by the equation sinh x = 12(ex - e-x).
- The hyperbolic cosine, defined by the equation cosh x = 12(ex + e-x).
- The hyperbolic tangent, defined by the equation tanh x = sinh x/cosh x.
- The hyperbolic cotangent, defined by the equation coth x = cosh x/sinh x.
- The hyperbolic secant, defined by the equation sech x = 1/cosh x.
- The hyperbolic cosecant, defined by the equation csch x = 1/sinh x.

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The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.