dihedral angle

Two distinct half-planes, emanating from a same line l, the space (3) into two regions called dihedral anglesMathworldPlanetmath.  The line l is the edge of the dihedral angle and the bounding half-planes are its sides.

The angle, which the sides of a dihedral planes separate from a normal planeMathworldPlanetmathPlanetmath of the edge, is the normal sectionMathworldPlanetmath of the dihedral angle.  Apparently, all normal sections are equal.  According to the of the normal section, the dihedral angle may be called acute, right, obtuse, straight, skew (http://planetmath.org/ConvexAngle), convex and concave.  Unlike the angle between two planes, a dihedral angle may be over 90 .

If two planes intersect each other and if one of the four dihedral angles formed is right, then also the others are right.  Then we say that the planes are perpendicularPlanetmathPlanetmath to each other.

Title dihedral angle
Canonical name DihedralAngle
Date of creation 2013-03-22 18:48:07
Last modified on 2013-03-22 18:48:07
Owner pahio (2872)
Last modified by pahio (2872)
Numerical id 9
Author pahio (2872)
Entry type Definition
Classification msc 51M04
Related topic NormalSection
Related topic PerpendicularityInEuclideanPlane
Related topic TrihedralAngle
Related topic SolidAngle
Defines edge
Defines side
Defines normal section
Defines concave
Defines perpendicular
Defines perpendicular planes