\begin{definition}[Definition:Diameter of Hyperbola/Also defined as]
Some sources define the '''diameter''' of a hyperbola $\KK$ as a chord of $\KK$ which passes through the center of $\KK$:
However, while it is true that such a chord is indeed a '''diameter''' of $\KK$, not all '''diameter''' of $\KK$ are chords of $\KK$.
For example:
:240px
where it can be seen that the diameter (red) of the hyperbola (blue) defined by the parallel chords is not actually itself a chord of $\KK$.
\end{definition}