RegionFarthestDistance

RegionFarthestDistance[reg1, reg2] gives the farthest distance between points in the regions reg1 and reg2.

Examples

Farthest distance between two disks:

RegionFarthestDistance[Disk[{0, 0}], Disk[{5, 0}]]
(* 7 *)

Farthest distance between a point and a region:

RegionFarthestDistance[Point[{0, 0}], Rectangle[{1, 1}, {3, 3}]]

Between two triangles:

RegionFarthestDistance[
  Triangle[{{0, 0}, {1, 0}, {0, 1}}],
  Triangle[{{2, 2}, {3, 2}, {2, 3}}]
]

Please visit the official Wolfram Language Reference for more details.