Director Circle

Director Circle

For the ellipse:

$$\frac{x^2}{a^2}+\frac{y^2}{b^2}=1$$

the director circle is:

$$x^2+y^2=a^2+b^2$$

Terminology

- Director circle → Locus of the intersection point of two perpendicular tangents to the ellipse.

Usage

- Used in problems involving pairs of perpendicular tangents.