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Hyperbolic functions

math Maturity 7-9 Next article →

Mathematics helps us describe the shapes of the world.

sinh cosh tanh
sinh cosh tanh

Most people learn about circles first. We use trigonometric functions to measure parts of a circle. However, math also looks at a different curve called a hyperbola.

Circular and hyperbolic angle
Circular and hyperbolic angle

Hyperbolic functions are like cousins to those circle functions. Instead of using a circle, they use a hyperbola. They work with a special kind of angle. This angle is measured by the area of a shape called a hyperbolic sector.

Hyperbolic functions-2
Hyperbolic functions-2

This area tells us how much the angle has grown.

These functions work in many different ways. You can find them in many math equations. For example, they help solve equations about cubes. They also help with Laplace's equation. This equation is very important in physics. It helps scientists study how heat moves from place to place. It also helps them study how water flows in fluids.

Cartesian hyperbolic rhombus
Cartesian hyperbolic rhombus

They even help explain how electricity and magnetism work. One famous use is describing a catenary. A catenary is the curve a heavy chain makes when it hangs freely between two points.

People have been curious about these shapes for hundreds of years. Gerardus Mercator used them around 1566 for his maps. Isaac Newton wrote about them in his famous book in 1687. Later, Vincenzo Riccati helped name them in 1757. He used specific names for the hyperbolic functions. In 1759, Daviet de Foncenex showed how they connect to circle functions. Then, Johann Heinrich Lambert organized them in the 1760s.

Complex Sinh
Complex Sinh

He changed the names to the ones we use today. He gave credit to Riccati for the original ideas.

There are several main hyperbolic functions to know. The two most basic ones are hyperbolic sine and hyperbolic cosine.

Hyperbolic and exponential; sinh
Hyperbolic and exponential; sinh

You can also use hyperbolic tangent. Other versions include hyperbolic cotangent, hyperbolic secant, and hyperbolic cosecant.

Hyperbolic and exponential; cosh
Hyperbolic and exponential; cosh

These functions are closely tied to the exponential function. For instance, hyperbolic sine is the odd part of an exponential function. Hyperbolic cosine is the even part. This connection makes them very powerful for solving hard math problems.

Hyperbolic functions connect to things you might already know. They relate to the way things grow or change. They also connect to complex numbers. In complex analysis, these functions appear when we use imaginary angles.

Complex Cosh
Complex Cosh

They can even be seen in the way light or energy moves. Even though they seem different from circles, they follow many of the same rules. This makes them a natural part of how we study geometry and science. They turn the curves of a hyperbola into something we can measure and understand.

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🖼️ Images & Media (13)
File:sinh cosh tanh.svg
sinh cosh tanh.svg
File:Hyperbolic functions-2.svg
Hyperbolic functions-2.svg
File:Cartesian_hyperbolic_rhombus.svg
Cartesian_hyperbolic_rhombus.svg
File:Hyperbolic and exponential; sinh.svg
Hyperbolic and exponential; sinh.svg
File:Hyperbolic and exponential; cosh.svg
Hyperbolic and exponential; cosh.svg
File:csch sech coth.svg
csch sech coth.svg
File:Circular and hyperbolic angle.svg
Circular and hyperbolic angle.svg
File:Complex Sinh.jpg
Complex Sinh.jpg
File:Complex Cosh.jpg
Complex Cosh.jpg
File:Complex Tanh.jpg
Complex Tanh.jpg
File:Complex Coth.jpg
Complex Coth.jpg
File:Complex Sech.jpg
Complex Sech.jpg

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