Assertion: tetrahedron's vertex | /r/HasProperty | arranged as regular polygon
Facets:
Source sentences:
text: It is also part of the family of 8 convex deltahedra (because it is convex and all its faces are equilateral triangles), and it is the first member of the infinite family of pyramids (one of the vertices shares identical edges with all the other vertices, which are arranged as a regular polygon).