The sum of all the interior angles of a regular polygon is $1260^{\circ}$, then find the numbers of sides.


Given: The sum of all the interior angles of a regular polygon is $1260^{\circ}$.

To do: To find the number of sides in the given polygon.

Solution:

As known that, Sum of measures of all interior angles of polygons $=( 2n−4)\times90^o$
  
Given, interior angle$=1260^o$
 
$\Rightarrow 1260=( 2n−4)×90^o$
 
$\Rightarrow 2n-4=\frac{1260}{90}$

$\Rightarrow 2n−4=14$

$\Rightarrow 2n=14+4$

$\Rightarrow 2n=18$

$\Rightarrow n=\frac{18}{2}$

$\Rightarrow n=9$
Therefore, the number of sides in a polygon is $9$.

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Updated on: 10-Oct-2022

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