數學一問？？？快！！！！！！！！！一個正ｎ邊形每個內角的大小是每個外角的９倍，求ｎ的值？？？？？　　ｈｅｌｐ

180(n-2) / n = 360*9/n
180n-360 = 3240
180n = 3600
n = 20

This is a 20-sided polygon

((n-2)*180)/n=9(360/n)
(180n-360)/n=3240/n
180n-360=3240
180n=3600
n=20

2008-04-10 17:45:56 補充：
So,this is a 20-sided polygon.