Question

find the number of side in a polygon if the sum of its interior angle is 3420°

Answer 1

given sum of the interior angle is 3420 and
we know that

3420=(n-2)x180

3420=180n-180x2

3420=180n-360

3420+360=180n

3780=180n

n=3780/180=21

therefore the number of side is 21