Remember my post about Sangakus?

Some time ago our local math association PRIME organized **Soiree Sangaku**, where the participants could investigate 30 of these Japanese puzzles. Try to solve these for yourselves!

I call the first one “*one rule to Ring them all*”. The puzzle is to find (and prove) the relation between the rings. In the second and third one, try find a relation between the radii of the orange circles. Warning: the latter aren’t easy at all… Good luck!

If you like these problems but got stuck at some point,

don’t hesitate to contact me ;)