a polygon with equal sides and equal angles is called a regular polygon (polygon: the number of sides is greater than or equal to 3). the center of the circumcircle of a regular polygon is called the center of the regular polygon. the length of the line connecting the center to the vertices of a regular polygon is called the radius. the distance between the center and the sides is called the edge-center distance. the axis of symmetry of a regular polygon - odd-numbered sides: connecting a vertex and the midpoint of the side opposite the vertex, which is the axis of symmetry; even-numbered sides: connecting the midpoints of two opposite sides, or connecting two symmetrical vertices. they are all axes of symmetry. the number of sides of a regular n-sided polygon is n and the number of axes of symmetry is n.