Question

The sum of interior angles of a polygon is 1620° What type of polygon is this?

Answer 1

Sum of interior angles $=(n-2)\times {180}^o$
where $n$ is the total number of sides.

$\Rightarrow {1620}^o=(n-2)\times {180}^o$
$\Rightarrow n-2=\frac{{1620}^o}{{180}^o}=9$
$\Rightarrow n=9+2=11$

$\therefore$ The polygon has 11 sides.
11 sided polygon is called hendecagon.