3. Rotations
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Rotational symmetry means that you can spin the figure 180^(∘) or less so that it maps onto itself.
D and G
Consider the given pentagon.
Notice that if we draw a circle in the middle of the pentagon we obtain five congruent angles.
Since a circle is 360^(∘), we know that the measure of each angle is equal to 72^(∘). 360^(∘)/5= 72^(∘) Then, if we rotate the pentagon by 72^(∘), it will map onto itself.
The same is true if we rotate the image 144^(∘). Therefore, the correct options are D and G, respectively.