the total angel of any polygons is (n as the totap side of the polygon)
(n - 2) x 180°
now we can substitute 120° into this formula
(n - 2) x 180° / n = 120° (because we're calculating each angle from the polygon, so we need to divide the equation by n)
(180n - 360) = 120n
180n - 120n = 360
60n = 360
n = 6
a 6 side polygon is hexagon.