Answer:
9
Step-by-step explanation:
Rotational symmetry is when a shape has the same orientation after being rotated.
For example, an equilateral triangle rotated 120° will line back up with itself. A square rotated 90° will also return to its original orientation. Same with a pentagon rotated 72°.
Basically, an n-gon rotated by a multiple of 360°/n will return to its original position.
θ = k 360°/n
For the first rotation:
160° = k 360°/n
160 / 360 = k / n
4/9 = k/n
For the second rotation:
120° = k 360°/n
120 / 360 = k / n
1/3 = k/n
For the third rotation:
80° = k 360°/n
80 / 360 = k / n
2/9 = k/n
For the fourth rotation:
280° = k 360°/n
280 / 360 = k / n
7/9 = k/n
The total rotation angle is -160°.
160 = k 360/n
160 / 360 = k / n
4/9 = k/n
Comparing the denominators, n must be the smallest multiple of 3 and 9. Therefore, n = 9.
