Assertion: tetrahedron's face | /r/CapableOf | call inscribed sphere
Facets:
Source sentences:
text: For any regular polyhedron, three spheres can be commonly defined: one that passes through all the vertices, called circumscribed sphere or circumsphere, one that passes through the centroids of all faces, called inscribed sphere or insphere, and one that passes through the middles of all edges, called midsphere.