Given: an n-gon prove: the sum of the measures of the interior angles is 180(n – 2)°. complete the missing parts of the paragraph proof. we are given an n-gon, which has n sides and n vertices. if we choose one of the vertices, we can draw diagonals. these diagonals form triangles. the sum of the interior angle measures of a triangle is degrees. n – 2 triangles would have an interior angle measure sum of . therefore, the sum of the measures of the interior angles of an n-gon is 180(n – 2)°. word bank: n - 2n - 3180 (n - 2)180 blank 1: