Polygon abcdef is a regular polygon. if point o is located at the center of the polygon, what degree of rotation about point o will carry the polygon onto itself?

How do you find the distance of each number from the mean

Round to the nearest ten thousandth.i dont get this

An angle bisector ac divides a trapezoid abcd into two similar triangles ? abc and ? acd. find the perimeter of this trapezoid if the leg ab=9 cm and the leg cd=12 cm.