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 Question from Karan: Prove that a convex polygon cannot have more than three acute internal angles.

Hi Karan,

First look at Walter's response to a question about the external angles of a convex polygon where he shows that the sum of the measures of the external angles in $360^{0}.$

In my diagram below $P, Q$ and $R$ are adjacent vertices of a convex polygon where the interior angle is acute.

What can you say about the external angle at $Q?$ Suppose there are 4 vertices of the convex polygon where the interior angle is acute.

Penny

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