OABC is a parallelogram.CD:DB=3:2,BE:EA=2:1.(→OD)=u and (→OE)=v are given.Express (→OA) and (→OC) in terms of u and v
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A.maths
2008-01-08 2:13 am
回答 (1)
2008-01-08 2:52 am
✔ 最佳答案
v=→OA+→AE=→OA+1/3 →OC..................(1)
u=→OC+→CD
=→OC+3/5 →OA...................(2)
by (1), →OA=v+1/3 →OC............(3)
sub.(3)into (2),u=→OC+3/5(v+1/3 →OC)
= 6/5 →OC+3/5v
→OC=(u-3/5v)5/6
sub. →OC=(u-3/5v)5/6 into (1),v=→OA+1/3(u-3/5v)5/6
=→OA+5/18(u-3/5v)
→OA=v - 5/18(u-3/5v)
希望幫到你 ^^
參考: 自己
收錄日期: 2021-04-13 14:53:49
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080107000051KK02616