a regular polygon of N sides is such that each interior angle is 120 degree greater than the exterior angle find: (1) the value of N (2) the sum of all The interior angle

Answer 1

measure of each exterior angle = 360 / N

measure of each interior angle = 180(N-2) / N

So, 180(N-2)/N = 360/N + 120

180(N-2) = 360 + 120N

60N = 720

N = 12

Sum of interior angles = 180(N-2) = 1800 degrees