Central Angle of a Regular Polygon

Definition:   (Billstein, Libeskind, and Lott) An angle whose vertex lies at the center of the polygon and whose sides intersect two adjacent vertices of the polygon. 

 

Example:

The angle <P2OP1 is a central angle of the given pentagon.  The central angle measures 72 degrees because 360 divided by 5 (the number of sides) equals 72.