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A figure in a plane has rotational symmetry when the figure can be mapped onto itself by a rotation of 180^(∘) or less.
A,B, D
A figure in a plane has rotational symmetry when the figure can be mapped onto itself by a rotation of 180^(∘) or less.
Regarding the first figure, A, we see that if we rotate it by 180^(∘), it will map onto itself.
Moving on to the second figure. By drawing segments from the pentagons vertices to it's midpoint, we create 5 isosceles triangles with vertex angles of 3605=72^(∘). Therefore, by rotating the pentagon by 72^(∘), it will map onto itself.
Do not try and rotate the half-moon. Instead only try to realize it has no rotational symmetry. As for the cross, we can see from the diagram below that it has a rotational symmetry of 90^(∘)
