The lengths of the tangents from a point 
to a conic 
are proportional to the cube roots
of the radii of curvature of 
at the corresponding points of contact.
Liouville's Conic Theorem
See also
Conic SectionExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Liouville's Conic Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LiouvillesConicTheorem.html