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Illustrative Mathematics
Illustrative Mathematics: G Co Symmetries of a Quadrilateral I
Suppose ABCD is a quadrilateral for which there is exactly one rotation, through an angle larger than 0 degrees and less than 360 degrees, which maps it to itself. Further, no reflections map ABCD to itself. What shape is ABCD? Aligns...
University of Georgia
University of Georgia: Inter Math: Angle of Rotation
This site gives a definition of angle of rotation and provides some examples. There is also an interactive activity in which a JavaSketchPad page is provided for you to explore rotations. In addition, be sure to follow the links to...