Infinite plane geometric region.
InfinitePlane[{p1, p2, p3}]
InfinitePlane[p, {v1, v2}]
Graphics3D[InfinitePlane[{{1, 0, 0}, {1, 1, 1}, {0, 0, 1}}]]
→ -Graphics3D-Show[ill, Graphics3D[InfinitePlane[{{1, 0, 0}, {1, 1, 1}, {0, 0, 1}}]]]
→ -Graphics3D-Show[ill, Graphics3D[InfinitePlane[{1, 0, 0}, {{0, 1, 1}, {-1, 0, 1}}]]]
→ -Graphics3D-