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Hyperbolic Functions and Their Properties

Hyperbolic functions are a set of mathematical functions that closely resemble trigonometric functions but are defined using exponential functions. These functions include hyperbolic sine, hyperbolic cosine, hyperbolic tangent, and hyperbolic cotangent. Hyperbolic functions are widely used in advanced mathematics, physics, engineering, and differential equations. This article introduces hyperbolic functions, their definitions, identities, and key properties.

Hyperbolic functionsHyperbolic sine and cosineExponential functions

~2 min read • Updated Feb 4, 2026

1. Introduction to Hyperbolic Functions


Hyperbolic functions are mathematical functions defined using exponential expressions. Although their names resemble trigonometric functions, they are related to the geometry of a hyperbola rather than a circle.


These functions are typically denoted by adding the letter h to trigonometric function names.


2. Definition of Hyperbolic Sine


The sinh x function is defined as:


sinh x = (e^x - e^(-x)) / 2

This function is defined for all real values of x.


3. Definition of Hyperbolic Cosine


The cosh x function is defined as:


cosh x = (e^x + e^(-x)) / 2

The value of cosh x is always greater than or equal to 1.


4. Definition of Hyperbolic Tangent


The tanh x function is the ratio of hyperbolic sine to hyperbolic cosine:


tanh x = sinh x / cosh x

The domain of this function is all real numbers, and its range lies between -1 and 1.


5. Definition of Hyperbolic Cotangent


The coth x function is defined as:


coth x = cosh x / sinh x

This function is undefined at x = 0.


6. Important Hyperbolic Identities


Hyperbolic functions satisfy identities similar to trigonometric identities.


cosh²x - sinh²x = 1

1 - tanh²x = 1 / cosh²x

coth²x - 1 = 1 / sinh²x

7. Differences Between Hyperbolic and Trigonometric Functions


Unlike trigonometric functions, which are periodic, hyperbolic functions are not periodic and exhibit exponential growth or decay.


8. Applications of Hyperbolic Functions


Hyperbolic functions are widely used in solving differential equations, modeling physical systems, electrical engineering, special relativity, and various applied mathematics problems.


Conclusion


Hyperbolic functions form an essential part of advanced mathematics. Despite their similarity in naming to trigonometric functions, they have distinct properties and applications rooted in exponential behavior.


Written & researched by Dr. Shahin Siami

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