Jawapan

2015-01-29T18:47:34+08:00
(9-2)x180

formula : (n-2)x180

n=nilai sudut
2015-01-29T18:54:20+08:00
(n - 2) × 180 darjah
         n

= (9 - 2) × 180 darjah
              9
= 7 × 180 darjah
         9
= 140 darjah