在圖中，求DE
http://www.u-discuss.net/upload/file/20070313192005.jpg
在圖中，求DE
2007-03-14 3:21 am
回答 (2)
2007-03-14 3:31 am
✔ 最佳答案
∠ABD=∠ACE=>BD//CE
=>△ABD相似於△ACE
=>BD:CE=AD:AE
BD=4cm}
CE=6cm}
AD=5cm}
=>AE=7.5cm}
AD=5cm}
=>DE=2.5cm
2007-03-15 13:36:56 補充：
步驟如下:1)先找出兩相同的角:∠ABD=∠ACE2)從而找出平衡線BD//CE3)再找出兩相似三角形△ABD~△ACE4)列出比例式BD:CE=AD:AE5)根據題目的條件,算出DE=2.5cm
2007-03-14 3:30 am
Let x be leght
Step1: 4:6=5:X
Step2:
4 5
-- = --
6 X
Step3:
4X = 30
X = 7.5
So, according to this DE = 7.5-5=2.5
The Answer: DE is 2.5cm
Step1: 4:6=5:X
Step2:
4 5
-- = --
6 X
Step3:
4X = 30
X = 7.5
So, according to this DE = 7.5-5=2.5
The Answer: DE is 2.5cm
參考: ME...
收錄日期: 2021-04-23 16:47:10
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070313000051KK03243