Rotational symmetry means that you can spin the figure 180^(∘) or less so that it maps onto itself.
Does the figure have rotational symmentry? Yes Rotations that map the figure onto itself: Rotations of 72^(∘) and 144^(∘) about the center.
Practice makes perfect
Consider the given start. If we connect each of the five points with the center, we create 5 congruent angles. Knowing that a full turn is 360^(∘), we can calculate the measure of each angle.
360^(∘)/5=72^(∘)
Therefore, a 72^(∘) rotation about the center maps the start onto itself.
The same is true if we rotate the figure 144^(∘) about the center.
