點做a?
http://www.uwants.com/attachments/day_070813/20070813_61f6a25adbab0045e9c4p9xCxRWF2QGv.jpg
a-maths!!!
2007-08-14 4:09 am
回答 (2)
2007-08-14 4:25 am
✔ 最佳答案
! a - b !^2= (a - b)(a - b)
= aa - ab - ba + bb
= aa - 2ab + bb
= !a!^2 - 2!a!!b!cos@ + !b!^2
bi)
! a - b !^2
= 3 - 2 sqrt(3) (2)cos30 + 4
= 7 - 6
= 1
! a - b ! = 1
ii)
! a - b !^2
= 3 - 2 sqrt(3) (2)cos150 + 4
= 7 + 6
= 13
! a - b ! = sqrt(13), 根 13
唔係好難,好基本,你應該識
2007-08-22 7:56 am
話我運吉?
10 個負評你應得!
10 個負評你應得!
收錄日期: 2021-04-23 20:34:33
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070813000051KK05389