WOLFRAM|DEMONSTRATIONS PROJECT

Points around an Ellipse

​
semimajor axis: a
3.
semiminor axis: b
2.615
rotation angle: θ°
156.
Given an ellipse with semimajor axis
a
and semiminor axis
b
, what is the locus of points
P
in the plane of the ellipse such that there are two perpendicular tangents from
P
to the ellipse? The answer is a circle of radius
r=
2
a
+
2
b
as illustrated in this Demonstration.