\begin{definition}[Definition:Proportion/Perturbed]
Let $a, b, c$ and $A, B, C$ be magnitudes.
$a, b, c$ are '''in perturbed proportion''' to $A, B, C$ {{iff}}:
:$a : b = B : C$
:$b : c = A : B$
{{EuclidSaid}}
:''{{:Definition:Euclid's Definitions - Book V/18 - Perturbed Proportion}}''
{{EuclidDefRefNocat|V|18|Perturbed Proportion}}
Category:Definitions/Proportion
\end{definition}