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. 1-2 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(n2 - 2)