Circumsphere

Circumsphere[{p1, ..., pn+1}] gives the sphere that circumscribes the points pi in n dimensions.

Circumsphere[poly] gives the circumsphere of a polyhedron or polygon poly.

Examples

Circumsphere of a triangle:

Circumsphere[{{0, 0}, {1, 0}, {0.5, 1}}]
(* Sphere[{0.5, 0.375}, 0.625] *)

Circumsphere of a tetrahedron:

Circumsphere[{{0, 0, 0}, {1, 0, 0}, {0, 1, 0}, {0, 0, 1}}]

Please visit the official Wolfram Language Reference for more details.