More Nonagon Wonders (GoGeometry Action 176!)

Creation of this resource was inspired by a problem posted by Antonio Gutierrez (GoGeometry). You can move the LARGE WHITE POINTS anywhere you'd like at any time. Note: the pink point INSIDE this polygon is the center of the (soon-to-appear) circle. After interacting with this applet for a few minutes, please answer the questions that follow.


What is the measure of the pink angle? Explain how the applet suggests this is true.


How can we prove the measure of the pink angle IS what it is?


How can we formally prove the angle on the right side also has a measure equal to the measure of the pink angle?

Quick (Silent) Demo