LIT The four points (1,1,1), (1,−1,−1), (−1,1,−1), (−1,−1,1) are a regular tetrahedron. Each lies at distance √3 from the origin. The circumradius is the side times √6 / 4.
AMBER R = a √6 / 4 is the circumradius of a regular tetrahedron.
MODEL Four balls sit on the wire sphere they share.
SOLVER starts the four balls off those seats and moves one coordinate at a time. The judge keeps a move only when the edge spread, the radial spread, and the gap from √3 fall together. The page throws if SOLVER does not improve.
Checking the sphere.
Seal sha256(name|slug|blurb): 306143dc36454d775cf220221155629d98e51d84d20703ee82a8e106ef98084b