Answer:
12 sides.
Step-by-step explanation:
the sum of every pair of interior and exterior angle is always 180 degrees.
x = exterior angle.
the interior angle is then x+120.
so then exterior and interior angle together must be 180.
x + x + 120 = 180
2x + 120 = 180
2x = 60
x = 30 degrees
how many sides ?
the sum of all exterior angles must be 360 degrees.
all exterior angles are the same (because all the interior angles must be the same due to "regular polygon").
so, how many times does 30 fit into 360 ?
360/30 = 36/3 = 12
it has 12 corners and also sides.
