Retrieving "Right Circular Double Cone" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Ellipse

   Linked via "right circular double cone"

   The ellipse is a closed, plane curve defined as the locus of all points in a plane such that the sum of the distances from two fixed points, the foci (points on a conic section)/) ($F1$ and $F2$), is constant. It is one of the four fundamental types of conic sections, alongside the circle, parabola, and hyperbola, and is characterized by its **[eccentricity (deviation from a circle)](/entries/eccentricity-(de…