Given:
Sum of all the interior angles of a regular polygon is 1080°.
Measure of each side is 10 cm.
To find:
The perimeter.
Solution:
The sum of all interior angles of a regular polygon with n side is:
![S=(n-2)180^\circ](https://img.qammunity.org/2022/formulas/mathematics/high-school/baa8y1athir7cebuucbnupapv0qoykyg9d.png)
Sum of all the interior angles of a regular polygon is 1080°.
![1080^\circ=(n-2)180^\circ](https://img.qammunity.org/2022/formulas/mathematics/high-school/11cuzbfmkaap78c20cd7xbm8dqi6vxzc74.png)
![(1080^\circ)/(180^\circ)=n-2](https://img.qammunity.org/2022/formulas/mathematics/high-school/a9ayw6lpkq7zswc5gp0y8harn6s9qj4nxy.png)
![6+2=n](https://img.qammunity.org/2022/formulas/mathematics/high-school/2isl005g1y1kj89c89upbb2g3siduhxqn2.png)
![8=n](https://img.qammunity.org/2022/formulas/mathematics/high-school/87bqy70pprhdey1545izhc4u6g0ui6tvoo.png)
Number of sides of the regular polygon is 8. The measure of each side is 10 cm. So, the perimeter of the regular polygon is:
![\text{Perimeter}=\text{Number of sides}*\text{Measure of each side}](https://img.qammunity.org/2022/formulas/mathematics/high-school/m15pkjdflw9biuwk5duj8acgrihoul1iay.png)
![\text{Perimeter}=8* 10](https://img.qammunity.org/2022/formulas/mathematics/high-school/s4fkckykm4vtfmk434nvkbks0nd3btme8y.png)
![\text{Perimeter}=80](https://img.qammunity.org/2022/formulas/mathematics/high-school/emsdcpyvttadjr6hn46yjjucmd3049n6vc.png)
Therefore, the perimeter of the regular polygon is 80.