Double circular cone
= Double circular cone
{title2=$z^2=x^2+y^2$}
The union of the two infinite lateral conical sheets meeting at a common vertex is a double circular cone. The displayed example has axis $z$ and semi-angle $\pi/4$. It is smooth away from the vertex, where its defining <gradient> is nonzero. A <right circular cone> truncated on one side is a related bounded solid; this surface includes both axial directions and has no base disks.