What are the angles of rotational symmetry?

Angles of rotational symmetry are the angles by which you can turn a figure about its center of symmetry so that the rotated figure is indistinguishable from the original.

Example

A square has angles of rotational symmetry of 90°, 180°, and 270°. Rotating a square around its center by any of these angles gives you back exactly the same square.

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The number of angles of rotational symmetry (including 0°) is the degree of rotational symmetry. A square has rotational symmetry of degree 4.