Assertion: icosahedron's face | /r/HasProperty | abx
Facets:
Source sentences:
text: X. We are looking for the angle between the face ABX and the face AXE.
text: Then the angle BFE is the angle between the two faces ABX and AXE.
text: BF and FE are the altitudes of the faces ABX and AZE, and they have the length .