Answer :
well you have to use the equation (n-2(180)) where n represents the number of sides
so- 21 - 2 = 19 then multiply 19 x 180 = 3420
so the sum of all the interior angles in a 21-gon is equal to 3420 degrees
so- 21 - 2 = 19 then multiply 19 x 180 = 3420
so the sum of all the interior angles in a 21-gon is equal to 3420 degrees
we know that
Sum of the measures of the interior angles of a polygon of n sides is equal to
[tex](n-2)*180[/tex]
where
n is the number of sides
in this problem
[tex]n=21 \\ (21-2)*180=3420[/tex]°
Hence
sum of the measures of the interior angles of a 21 sided polygon is
[tex]3420[/tex]°
Sum of the measures of the interior angles of a polygon of n sides is equal to
[tex](n-2)*180[/tex]
where
n is the number of sides
in this problem
[tex]n=21 \\ (21-2)*180=3420[/tex]°
Hence
sum of the measures of the interior angles of a 21 sided polygon is
[tex]3420[/tex]°