Exercise 8 Page 973

Before we begin, recall that a figure in a plane has rotational symmetry if the figure can be mapped onto itself by a rotation between $0^{\circ }$ and $360^{\circ }$ about the center of the figure — the center of symmetry. Let's analyze the given figure.

Let's see if we can identify a point that will be the center of the figure, about which there is a rotation that maps the figure onto itself. Yes, it looks like there is!

We can see that the given figure maps onto itself $2$ times as it rotates from $0^{\circ }$ to $360^{\circ }.$ This is the order of symmetry.