The Sketchpad Applet below displays a
parallelogram and its image produced by rotating the parallelogram
about its center point. The angle of rotation, ZYX, can be changed
by dragging point X.
Drag point X to rotate the image
parallelogram A'B'C'D'. Determine all angles of rotation less than
360° for which the image parallelogram exactly coincides with
the pre-image parallelogram ABCD. The angle measures you determine
give the rotation symmetry for the parallelogram.
Drag a red vertex of parallelogram ABCD
until it appears to be a rectangle. Repeat step 2 and determine
the rotation symmetry for the rectangle.
Drag a red vertex of parallelogram ABCD
until it appears to be a rhombus. Repeat step 2 and determine the
rotation symmetry for the rhombus.
Drag a red vertex of parallelogram ABCD
until it appears to be a square. Repeat step 2 and determine the
rotation symmetry for the square.
