设多边形的内角和为S，边数为n，则S=（n－2）×180°．根据这个公式，已知多边形的边数可求内角和；反之，已知多边形的内角和可求边数．由于多边形的每一个内角和相邻的外角构成一个平角，可得多边形的外角和为360o．如果各外角相等，已知外角的度数或外角与内角度数之比，也 Let the interior angle of the polygon be S and the number of edges be n, then S=(n-2)×180°. According to this formula, it is known that the number of sides of a polygon can be calculated as the inner angle and the angle; on the contrary, the inner angle and the number of sides of the polygon can be known. Since each inner angle of the polygon and the adjacent outer angle form a flat angle, the outer angle of the polygon can be 360o. If the outer angles are equal, the ratio of the outer angle or outer angle to the inner angle is known.