You can put this solution on YOUR website! Regular convex polygons have exterior angles that add up to 360 degrees, and all the angles are congruent (congruent means they are identical)
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So in your problem, the polygon has exterior angles of 30 degrees. Les't solve this:
Sum of the angles of a polygor: 360
Number of sides of the polygon: n
Each exterior angle: 30 degrees
30n = 360 divide both sides by 30
n = 12 your polygon has 12 sides