EUCLIDEAN PARALLEL POSTULATE - University of Texas at Austin

be divided into n -2 triangles and the sum of the angles of the polygon is equal to the sum of the angles of the n-2 triangles. This proves the following result. 2.2.2 Theorem. The sum of the interior angles of an n-sided polygon, n ≥ 3 , is (n − 2) ⋅180 °. 2.2.2a Demonstration. ................
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