Assertion: tetrahedron's edge | /r/HasAspect | equal lengths
Facets:
Source sentences:
text: If four faces of a parallelepiped are rhombi, then all edges have equal lengths and all six faces are rhombi; it follows that if two pairs of opposite edges in a tetrahedron are perpendicular, then so is the third pair, and the tetrahedron is orthocentric.