第1个回答 2010-08-28
AB^2=AC^2+BC^2
AB^2=2.1^2+2.8^2=12.25
AB=3.5
S=AB*BC/2=2.1*2.8/2=2.94
CD=2S/AB=2*2.94/3.5=1.68
AD^2=AC^2-CD^2
=2.1^2-1.68^2
=4.41-2.8224
=1.5876
AD=1.26
BD=AB-AD=3.5-1.26=2.24
第2个回答 2010-08-28
1 ∵ac*ac+bc*bc=ab*ab
∴ab*ab=2.1*2.1+2.8*2.8
=12.25
ab=3.5
∵ac*bc=ab*cd
∴cd=ac*bc/ab
=1.68
2 再由勾股定理得ad*ad=ac*ac-cd*cd
=2.8224
ad=1.26
同理db=2.24
第3个回答 2010-08-28
AB等于AC与BC的平方和再开平方根,3.5cm.
AD=1.26cm,BD=2.24cm
第4个回答 2010-08-28
直接上图
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/b999a9014c086e0646b6ce3f02087bf40ad1cbac?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
第5个回答 2010-08-28
AB的长你会的
然后