\begin{definition}[Definition:Secant Function/Real]
Let $x \in \R$ be a real number.
The real function $\sec x$ is defined as:
:$\sec x = \dfrac 1 {\cos x}$
where $\cos x$ is the cosine of $x$.
The definition is valid for all $x \in \R$ such that $\cos x \ne 0$.
Category:Definitions/Secant Function
\end{definition}