A catenary is the curve formed by a perfectly flexible, uniform chain suspended under its own weight and acted upon by gravity. It is mathematically described by the hyperbolic cosine function.
Hyperbolic Functions: Functions that include hyperbolic sine ($\sinh$), cosine ($\cosh$), tangent ($\tanh$), and their inverses. They are analogs of trigonometric functions but for a hyperbola.
$\cosh(x)$: $\cosh(x)$ or hyperbolic cosine is defined as $\cosh(x) = \frac{e^x + e^{-x}}{2}$. It describes the shape of a catenary.
$\sinh(x)$: $\sinh(x)$ or hyperbolic sine is defined as $\sinh(x) = \frac{e^x - e^{-x}}{2}$. It is related to $\cosh(x)$ through various identities.