中3數......................

2007-05-25 8:32 am
1 4邊形ABCD的頂點是A(0,0)和B(2,1),C(1,3)和D(-2,4),求証ABCD梯形。

回答 (2)

2007-05-25 7:12 pm
✔ 最佳答案
要證明他是梯形,先要證明一組對邊是平行。另外兩邊不是平行
slope of BC=(3-1)/(1-2)=-2
slope of AC=(1-0)/(2-0)=1/2
slope of AD=(4-0)/(-2-0)=-2
slope of BD=(4-1)/(-2-2)=3/-4
Thus, slope of BC=slope of AD
slope of AC is not equal to BD
ABCD is a 梯形
slope of line=(y2-y1)/(x2-x1)
2007-05-25 8:49 am
梯形的定義

一個四邊形其中一組對邊平行

所以你要証明

slope of AD = (4-0)/(-2-0) = -2
slope of BC = (3-1)/(1-2) = -2

仲未夠
仲要証埋slope of AB =/= slope of CD
(如果等於的話就會變左平行四邊形)


收錄日期: 2021-04-23 20:32:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070525000051KK00140

檢視 Wayback Machine 備份