Rotational Symmetry

A figure has rotational symmetry if it can be mapped onto itself (every point rotates to another point on the figure) by a positive rotation of 180^o or less about a point called the "center" of the figure.  The angle of rotation is the smallest positive angle through which this happens.

For example, the following "windmill" has rotational symmetry and maps onto itself when rotated through an angle of 60^o, 120^o, or any other multiple of 60^o:

The angle of rotation for this figure is 60^o.

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