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
360 Degrees of Billy Paul was similarly enthusiastic in discussing how Paul's sound developed over the years from the early club jazz of "Feelin' Good at the Cadillac Club" (1968) to the merging of jazz and soul on "Going East" (1971): "and then we did Billy's "360 Degrees" album and it all came together with "Me & Mrs. Jones." During his appearance on "Soul Train" in October 1972, Paul was asked by host Don Cornelius whether he had a jazz background. Paul used the opportunity to promote his new album and highlight its diverse styles: “That's very correct. I've been singing since I was 11.