\begin{definition}[Definition:Conic Section/Intersection with Cone/Degenerate Hyperbola]
{{:Definition:Conic Section/Intersection with Cone}}
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Let $\phi < \theta$, that is: so as to make $K$ a hyperbola.
However, let $D$ pass through the apex of $C$.
Then $K$ degenerates into a pair of intersecting straight lines.
\end{definition}