Assertion: tetrahedron's vertex | /r/HasProperty | angled
Facets:
value: right
type: DEGREE
Source sentences:
text: If you are unsure what I'm talking about: In a tetrahedron that has a right angled vertex (all three edges from that vertex at 90 degree angle from one another), the square of the area of the opposite face is equal to the sum of the square of all three other face's area.