Assertion: tetrahedron's angle | /r/HasProperty | sixty degrees
Facets:
Source sentences:
text: A regular tetrahedron is a special case of both the general tetrahedron and the isosceles tetrahedron for which all four triangular faces are not only congruent, but are also equilateral triangles, i.e. triangles for which all three sides are the same length, and all internal angles are sixty degrees (60°).