You can put this solution on YOUR website! Find the degree measure of one interior and one exterior.
( 20 sides polygon)
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The sum of the exterior angles is 360 degrees.
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Each exterior angle has measure = 360/20 = 18 degrees
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Each interior angle is the supplement of an exterior angle.
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Each interior angle is 180-18 = 162 degrees
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Cheers,
Stan H.