Rotational symmetry

if you can rotate (or turn) a figure around a center point by fewer than 360° and the figure appears unchanged, then the figure has rotation symmetry. The point around which you rotate is called the center of rotation, and the smallest angle you need to turn is called the angle of rotation.




This figure has rotation symmetry of 72°, and the center of rotation is the center of the figure:
for details
www.numeracysoftware.com/rotational%20symmetry.pps