| 释义 |
axis of symmetry An axis of symmetry might refer to reflective symmetry of a planar figure or to rotational symmetry. A line in the plane is an axis of symmetry of a figure if the figure is an invariant set under reflection in that line. Or an axis of symmetry might refer to a line such that an object is an invariant set for some non-trivial rotations about that line. There may be finitely many such rotations, as with a cube around its various axes of symmetry, or infinitely many, as with a cylinder about its axis.
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