Question 560488
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Not enough information.  The total of the measures of the external angles of any polygon is 360 degrees, but without knowing that this is a <i>regular</i> polygon, just knowing that one of the exterior angles measures 20 degrees doesn't tell you anything about the measures of the rest of them.  On the other hand if it is a regular polygon, then you know that all of the external angles are the same so you just divide 360 by 20.

John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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