Question

complete the following sentence. the figure below has rotational symmetry. ° is the smallest possible rotation that results in the figure being mapped onto itself.

Explanation:

Step1: 明确旋转对称概念

旋转对称是图形绕某点旋转一定角度后与自身重合。

Step2: 分析五角星

五角星有5条对称轴，绕中心旋转时，旋转角度为$\frac{360^{\circ}}{5}=72^{\circ}$的整数倍能与自身重合。

Step3: 求最小旋转角度

所以最小旋转角度是$72^{\circ}$。

Answer:

$72$