Calculate the measure of the angle "x" - from "Puzzle Sphere" of "Medium"

I've seen it in many places. There's a very different solution based on constructing a regular polygon around vertex A (S in my version):

1746925909446.png
Most of this is easy once you see the idea; the hard part is to explain concisely why T and U both lie on RF (which is the reflection of BN actoss diameter AJ, and of DP across diameter BK, which contain U and T respectively).
 
Top