Prove that the sum of the exterior angles at opposite vertices of any quadrilateral es equal to the sum of the interior angles at the other two vertices.(adsbygoogle = window.adsbygoogle || []).push({});

THIS question is REAly really really really getting me frustrated...

The way we're suppost to do it is like this....

180n-360 is the interior angles and exterior angles is 180n-180(n-2)

From there I don't know.....

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# Help with a Proof

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