Definition:Dandelin Spheres/Ellipse

Definition

Let $\CC$ be a double napped right circular cone with apex $O$.

Let $\PP$ be a plane which intersects $\CC$ to form an ellipse.

The Dandelin spheres $\SS$ and $\SS'$ appear as follows:

Also see

• Dandelin's Theorem

• Results about Dandelin spheres can be found here.

Source of Name

This entry was named for Germinal Pierre Dandelin.

Sources

• 1933: D.M.Y. Sommerville: Analytical Conics (3rd ed.) ... (previous) ... (next): Chapter $\text {IV}$. The Ellipse: $1 \text a$. Focal properties
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): Dandelin sphere
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): Dandelin sphere