Concave polygon does not contain all other vertices in its edges and interior. The convex hull of the concave polygon's vertices, and that of its edges, contains points that are exterior to the 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
The Three Degrees at The Royal Albert Hall" (aka "An Evening with The Three Degrees"), was recorded in October 1979 in which the trio were backed by the Royal Philharmonic Orchestra. In 1980, the compilation album "Gold" was released and became a UK Top 10 hit. Featuring one side of their hits on the Ariola label between 1978–79, and one side of live recordings from their 1979 Royal Albert Hall television special, this would be the trio's second "best of" compilation to make the UK Top 10 in less than two years, after CBS released "A Collection of their 20 Greatest Hits" in