Question

Find the number of a polygon whose sum of interior angles is ${1440}^o$.

Answer 1

The interior angle of a polygon is $=(n-2){180}^{\circ }$

$\Rightarrow {1440}^{\circ }=(n-2){180}^{\circ }$

$\Rightarrow n-2=\frac{1440}{180}=8$

$\therefore n=8+2=10$ sides.