Concave polygon Concave polygon A simple polygon that is not convex is called concave, non-convex or reentrant. A concave polygon will always have at least one reflex interior angle—that is, an angle with a measure that is between 180 degrees and 360 degrees exclusive. Some lines containing interior points of a concave polygon intersect its boundary at more than two points. Some diagonals of a concave polygon lie partly or wholly outside the polygon. Some sidelines of a concave polygon fail to divide the plane into two half-planes one of which entirely contains the polygon. None of these three statements holds for
Allied Masonic Degrees Allied Masonic Degrees The Allied Masonic Degrees (AMD) are a series of Masonic degrees conferred by "Councils of the Allied Masonic Degrees". The Allied Masonic Degrees form an appendant order of Freemasonry that exists in some Masonic jurisdictions; its degrees are conferred only by invitation. Councils of the Allied Masonic Degrees exist in Great Britain, the United States, Canada, France and Australia and their members also educate one another by presenting research papers on Freemasonry. The structure is very like that of the craft lodges, with the exception that the offices of Secretary and Treasurer may be combined in some