\begin{definition}[Definition:Diameter of Conic Section/Also defined as]
Some sources define the '''diameter''' of a conic section $\KK$ as a chord of $\KK$ which passes through the center of $\KK$.
This is a perfectly adequate definition of a '''diameter of an ellipse'''.
Indeed, in the context of a circle, this is how a '''diameter''' is routinely defined.
However, the definition does not work so well in the context of:
:a hyperbola, as it does not encompass diameters which are not chords
:a parabola, which does not have a center.
Hence, for the general conic section, and one that is not specifically a circle, this definition is not used on {{ProofWiki}}.
\end{definition}