(n) :
an angle formed by two intersecting straight lines; an angle formed by two intersecting planes, measured by the angle between two intersecting straight lines that are in respective planes and perpendicular to the intersection of the planes
(n) :
an angle formed by two intersecting straight lines; an angle formed by two intersecting planes, measured by the angle between two intersecting straight lines that are in respective planes and perpendicular to the intersection of the planes