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
900 Degrees on the Dance Club Songs chart the following year. UK CD Single German CD Single 900 Degrees "900 Degrees" is a song by German DJ and producer Ian Pooley. The song was released as a single from his sixth studio album, "Since Then", released in October 2001. Upon its release, the song peaked within the top 60 on the UK Singles chart and remained Pooley's highest-peaking UK single for more than a year, until his 2002 single "Piha" peaked higher. The song also entered the "Billboard" Hot Dance Breakouts Maxi-Single Sales chart, becoming his first chart entry there. "900 Degrees"