# GoGeometry Action 127!

- Author:
- Tim Brzezinski

- Topic:
- Geometry, Orthocenter

Creation of this applet was inspired by a problem posted by Antonio Gutierrez (GoGeometry).
You can move the

**2 LARGE VERTICES**of the triangle anywhere you'd like at any time. You can alter the size of the angle with**BLUE VERTEX**with the**BLUE SLIDER**. You can alter the size of the angle with**YELLOW VERTEX**using the**YELLOW SLIDER**.**How would you describe the phenomenon you see in your own words?****How can we formally prove this phenomenon to be true regardless of the locations of the orange point, the purple point, and the green point?**