Three circles (two with centre) and four line segments. Prove that, if the small circle is orthogonal to both wheels, then the wheels are also orthogonal to each other.
Scroll down for a solution to this problem.
Solution
Using the cyclic quadrilateral lemma, we have a2+b2=c2. So the radii of the green circles to their intersection point are orthogonal.
More solutions: https://x.com/Mirangu1/status/1938201163284754754