\begin{definition}[Definition:Inverse Ratio]
Let $R = a : b$ be a ratio.
Then the '''inverse ratio''' to $R$ is $b : a$.
{{EuclidSaid}}
:''{{Definition:Euclid's Definitions - Book V/13 - Inverse Ratio}}
{{EuclidDefRefNocat|V|13|Inverse Ratio}}
\end{definition}