Explanation

sum of the interior angles of a regular polygon = $( n - 2 ) \times 180 = 1080$

$n - 2 = \frac {1080}{180} = \frac{108}{18}$

$n - 2 = 6$

$n = 8$

one external angle = $\frac {360}{n}$

$\frac{360}{8}$ $= 45$

sum of the interior angles of a regular polygon = $( n - 2 ) \times 180 = 1080$

$n - 2 = \frac {1080}{180} = \frac{108}{18}$

$n - 2 = 6$

$n = 8$

one external angle = $\frac {360}{n}$

$\frac{360}{8}$ $= 45$