From a point inside a quadrilateral $($not on any diagonal$)$, we join the vertices of the quadrilateral. Prove that the sum of the lengths of these line segments is greater than the sum of the lengths of these diagonals.

Write by calculating the sum of measurement of eight interior angles of an octagon.

Write the measurement of each interior and each exterior angle of a regular polygon with $10$ sides.

Write by calculating the number of sides of a regular polygon where measurement of each interior angle is $120°$.

Write the sum of the measurement of the interior angles of Pentagon.

Write the sum of the measurement of the interior angles of Hexagon.

Write the sum of the measurement of the interior angles of Heptagon.

Write the sum of the measurement of the interior angles of Octagon.