how many sides does a regular polygon have if each exterior angle measures 30
The exterior angles of any regular or non-concave sided shape is 360 degrees
so, $${\frac{{\mathtt{360}}}{{\mathtt{30}}}} = {\mathtt{12}}$$ which is the answer.
If the exterior angle is 30, the interior angle is supplementary to this = 150
And we have
(n - 2)(180) / n = 150
(n - 2)(180) = 150n
180n - 360 = 150n rearrange
30n = 360 divide by 30 on both sides
n = 12 sides {a dodecagon}