# Animation 53

- Author:
- Tim Brzezinski

Shown in the applet below are a triangle, its circumcircle, and its 9-point circle. Point O is the triangle's orthocenter.
What special theorem about a triangle's 9-Point Circle is being dynamically illustrated below?
Note: Be sure to move the **BIG GREEN POINT** around! Also be sure to move the triangle's **gray vertices **anywhere you'd like!