Assertion: tetrahedron's face | /r/HasProperty | acute
Facets:
value: necessarily
type: DEGREE
Source sentences:
text: It might seem as if this derivation does not apply to obtuse triangles, because the "hypotenuse face" of a right tetrahedron is necessarily acute (i.e., each of its angles must be less than 90 degrees).
text: (easily follows that 4th face is an acute triangle).
text: The faces of an equifacial tetrahedron are necessarily acute triangles.
text: The faces are acute isosceles triangles.