👉 In mathematical terms, an "undersphere" is a subset of a three-dimensional space that is completely contained within another shape, such as a sphere. This concept arises from the idea of spheres being "under the surface," meaning they are not visible or accessible to the naked eye but can be observed through a lens. For example, consider a sphere with radius 1 unit in three dimensions (3D) and an undersphere that is centered at another point on this sphere. The undersphere would
