Answer: An nonagon is a regular shape of 9 sides with the same length.
As this has 9 sides, then the angle of rotational symmetry will be n*2π/9
where n is an integer.
writing it in degrees, the angles will have the for of n*360°/9
so the angles are:
n = 0 ------------- a = 0°
n = 1 -------------- a = 40°
n= 2 --------------- a = 80°
n= 3 --------------- a = 120°
..
and so on, adding by 40° each time.
so the answers are in the options that you give are 40°, 120°, 240°, 260° and 320°.
