f.2簡單polygon

1. An interior angle = (n - 2)(180*)/n

An exterior angle = 360*/n

So, (n - 2)(180*)/n = 5(360*)/n

(n - 2) = 10

n = 12

So, the regular polygon is a 12-side polygon


2. 2(360*)/n + 140* = (n - 2)(180*)/n

720* + n140* = n180* - 360*

40*n = 1080*

n = 27

So, the number of sides of the regular polygon is 27