As followS:
圖片參考：http://f.imagehost.org/0778/ScreenHunter_12_Jan_31_20_22.gif
maths~~~~~
2010-02-01 4:30 am
回答 (1)
2010-02-01 5:08 am
✔ 最佳答案
AF=FE=x (Given)BF=DF (Given)
<BAF=<DEF=90deg (Given)
△ABF ≒ △ EDF(RHS)
<AFB=<EFD
<BFD=180deg/3=60deg
<AFB+<EFD+<BFD=90deg
<AFB=15deg
x/BF=cos15deg
BF=x/cos15deg
參考: Hope can help you^^”
收錄日期: 2021-04-23 20:41:58
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100131000051KK03547