\begin{definition}[Definition:Right Circular Cone/Acute-Angled]
Let $K$ be a right circular cone.
Then $K$ is '''acute-angled''' {{iff}} the opening angle of $K$ is an acute angle.
{{EuclidSaid}}
:''{{Definition:Euclid's Definitions - Book XI/18 - Cone}}''
{{EuclidDefRefNocat|XI|18|Cone}}
Category:Definitions/Cones
\end{definition}