What is the definition of an ellipse for conic sections

The video tutorial explains the concept of an ellipse, comparing it to a circle. It defines an ellipse as a set of points where the sum of distances to two fixed points, called foci, is constant. The tutorial elaborates on the properties of ellipses, including the role of foci and how these properties differ from those of a circle. The video concludes by summarizing the key points and highlighting the similarities and differences between ellipses and circles.

Explain how the definition of an ellipse is similar to that of a circle.

What is the relationship between the distances D1, D2, D3, and D4 in the context of an ellipse?