Hyperbola: Reflective Property

In the applet below, a tangent is drawn to a yellow point on the hyperbola. Feel free to alter the location of this yellow point by moving the BIG BROWN POINTS. Feel free to change the locations of this hyperbola's foci as well. Interact with this applet for a few minutes, then answer the questions that follow.


Describe the phenomena you observe as best you can in your own words.


How could you formally prove your assertion?

Quick (Silent) Demo