Exercise 11.
Prove that the sum of the interior angles of a convex \(n\)-gon is \((n-2)\cdot 180^\circ\text{.}\) (A convex \(n\)-gon is a polygon with \(n\) sides for which each interior angle is less than \(180^\circ\text{.}\))
Prove that the sum of the interior angles of a convex \(n\)-gon is \((n-2)\cdot 180^\circ\text{.}\) (A convex \(n\)-gon is a polygon with \(n\) sides for which each interior angle is less than \(180^\circ\text{.}\))