# Cut-The-Knot Action 18!

- Author:
- Tim Brzezinski

Creation of this applet was inspired by a tweet from Alexander Bogomolny.
Shown below is a .
Suppose a

**rectangular hyperbola**.**A rectangular hyperbola is one whose semimajor and semiminor axes are equal.**Thus, its eccentricity**triangle**has 3 vertices that lie on such a**hyperbola**. How can we prove its**orthocenter**always lies on this**hyperbola**as well?