> with(geometry):
> RegularPolygon(P, 20, point(o,0,0), 10);

                                  P

> detail(P)
> ;

  name of the object:  P
        form of the object:  RegularPolygon2d
        the side of the polygon:  20*sin(1/20*Pi)
        the center of the polygon:  [0, 0]
        the radius of the circum-circle:  10
        the radius of the in-circle:  10*cos(1/20*Pi)
        the interior angle:  9/10*Pi
        the exterior angle:  1/10*Pi
        the perimeter:  400*sin(1/20*Pi)
        the area:  2000*sin(1/20*Pi)*cos(1/20*Pi)
        the vertices of the polygon:  [[10, 0], [10*cos(1/10*Pi), \
        10*sin(1/10*Pi)], [10*cos(1/5*Pi), 10*sin(1/5*Pi)], [10*co\
        s(3/10*Pi), 10*sin(3/10*Pi)], [10*cos(2/5*Pi), 10*sin(2/5*\
        Pi)], [0, 10], [-10*cos(2/5*Pi), 10*sin(2/5*Pi)], [-10*cos\
        (3/10*Pi), 10*sin(3/10*Pi)], [-10*cos(1/5*Pi), 10*sin(1/5*\
        Pi)], [-10*cos(1/10*Pi), 10*sin(1/10*Pi)], [-10, 0], [-10*\
        cos(1/10*Pi), -10*sin(1/10*Pi)], [-10*cos(1/5*Pi), -10*sin\
        (1/5*Pi)], [-10*cos(3/10*Pi), -10*sin(3/10*Pi)], [-10*cos(\
        2/5*Pi), -10*sin(2/5*Pi)], [0, -10], [10*cos(2/5*Pi), -10*\
        sin(2/5*Pi)], [10*cos(3/10*Pi), -10*sin(3/10*Pi)], [10*cos\
        (1/5*Pi), -10*sin(1/5*Pi)], [10*cos(1/10*Pi), -10*sin(1/10\
        *Pi)]]

> evalf(P[10]);

                                P[10]

> P[1];

                                 P[1]

> P.1
> ;

                                  P

> P.10;

                                 10 P

> evalf([[10, 0], [10*cos(1/10*Pi), 10*sin(1/10*Pi)], [10*cos(1/5*Pi), 10*sin(1/5*Pi)], [10*cos(3/10*Pi), 10*sin(3/10*Pi)], [10*cos(2/5*Pi), 10*sin(2/5*Pi)], [0, 10], [-10*cos(2/5*Pi), 10*sin(2/5*Pi)], [-10*cos(3/10*Pi), 10*sin(3/10*Pi)], [-10*cos(1/5*Pi), 10*sin(1/5*Pi)], [-10*cos(1/10*Pi), 10*sin(1/10*Pi)], [-10, 0], [-10*cos(1/10*Pi), -10*sin(1/10*Pi)], [-10*cos(1/5*Pi), -10*sin(1/5*Pi)], [-10*cos(3/10*Pi), -10*sin(3/10*Pi)], [-10*cos(2/5*Pi), -10*sin(2/5*Pi)], [0, -10], [10*cos(2/5*Pi), -10*sin(2/5*Pi)], [10*cos(3/10*Pi), -10*sin(3/10*Pi)], [10*cos(1/5*Pi), -10*sin(1/5*Pi)], [10*cos(1/10*Pi), -10*sin(1/10*Pi)]]);

  [[10., 0.], [9.510565163, 3.090169944], [8.090169943, 5.877852524],

        [5.877852522, 8.090169944], [3.090169938, 9.510565165],

        [0., 10.], [-3.090169938, 9.510565165],

        [-5.877852522, 8.090169944], [-8.090169943, 5.877852524],

        [-9.510565163, 3.090169944], [-10., 0.],

        [-9.510565163, -3.090169944], [-8.090169943, -5.877852524],

        [-5.877852522, -8.090169944], [-3.090169938, -9.510565165],

        [0., -10.], [3.090169938, -9.510565165],

        [5.877852522, -8.090169944], [8.090169943, -5.877852524],

        [9.510565163, -3.090169944]]

>