F.2 MATH
2012-02-02 5:40 am
If three times of an exterior angle of a regular polygon is 20 degree less than its interior angle, find the number of sides of the the regular polygon.
回答 (1)
2012-02-02 6:41 am
✔ 最佳答案
Let n be the number of sides of the regular polygon.Exterior angle = 360°/n
Interior angle = (2n - 4) x 90°/n
3 x (360/n) + 20 = (2n - 4) x 90/n
[3 x (360/n) + 20]n = [(2n - 4) x 90/n]n
1080 + 20n = 180n - 360
160n = 1440
n = 9
Hence, the number of sides of the regular polygon = 9
參考: 賣女孩的火柴
收錄日期: 2021-04-13 18:30:35
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120201000051KK00981