f.2 maths 1題20分
2008-03-27 10:01 pm
For a regular polygon, each interior angle of it is greater than each exterior angle by 100°. Find the number of sides of this polygon.
回答 (2)
2008-03-27 10:53 pm
✔ 最佳答案
因為我讀書o既時候係讀中文o既,所以我唔識英文係點答~不過希望都可以幫到你~
仲有我唔記得晒d定理個名,就算記得都係中文,記得自己加返,唔係冇分ga^^~
(留意我o係呢度打唔到(度)既符號,你都要自己加返)
設x為多邊形其中一個外角
x+(x+100)=180
2x+=80
x=40
設y is the number of sides of this polygon
xy=360(好似係多邊形外角和)
y=9
so the number of sides of this polygon is 9~
仲有咩唔識可以隨時問我^^
參考: 自己
2008-03-27 10:09 pm
let n= no. of sides and x = each size of ext. angle
then 180- x = each size of int . angle
hence (180-x) - x = 100(angle on a st. line)
180 - 2x = 100
80 = 2x
x = 40
since 40 n = 360 (angle sum of ext angle)
n = 9
then 180- x = each size of int . angle
hence (180-x) - x = 100(angle on a st. line)
180 - 2x = 100
80 = 2x
x = 40
since 40 n = 360 (angle sum of ext angle)
n = 9
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