Symmetry in a flag
The flag of Portugal has a cyclic symmetry of type C1: the are no rotations nor reflections that send the flag in itself (apart from the identity).
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The image belongs to the sections...:
1. (C1) (Symmetry)
Coat of arms, trade marks and flags (Anthology of images)
Coat of arms, trade marks and flags (Symmetry)
(2D geometry)