Assertion: tetrahedron | /r/HasProperty | disphenoid
Facets:
value: if
type: DEGREE
Source sentences:
text: A tetrahedron is a disphenoid if and only if its circumscribed parallelepiped is right-angled.
text: We also have that a tetrahedron is a disphenoid if and only if the center in the circumscribed sphere and the inscribed sphere coincide.
text: Another characterization states that if d 1 , d 2 and d 3 are the common perpendiculars of AB and CD; AC and BD; and AD and BC respectively in a tetrahedron ABCD, then the tetrahedron is a disphenoid if and only if d 1 , d 2 and d 3 are pairwise perpendicular.
text: If the four faces of a tetrahedron have the same perimeter, then the tetrahedron is a disphenoid.