Question #ffc86

1 Answer
Jul 29, 2017

N = 18
Sum of the interior angles = 16 x 180 = 2880

Explanation:

The external reflex angle = 200, then the extended side
leaves a 20 deg ( 200 - 180 ) angle with the side.
Thus the interior angle is 160 since it must be supplementary.
The sum of interior angles of a regular polygon = 180 ( N - 2 )
And for this problem, it also must = N ( 160 )
Equating these two facts => N = 18

Sum of interior angles = 180 ( 18 - 2 ) = 2880
Sum of interior angles = 18 ( 160 ) = 2880