如图，点L，M，N分别为△ABC三边BC，CA，AB上的点，且 BLBC=1 ， AMCA=m ， ANAB=n ，若 AL→ + BM→ + CN→ =0，求证：l=m=n．_刷题宝

题干

如图，点L，M，N分别为△ABC三边BC，CA，AB上的点，且

B

L

B

C

=1 ，

A

M

C

A

=m ，

A

N

A

B

=n ，若 AL→ + BM→ + CN→ =0，求证：l=m=n．

上一题下一题 0.0难度选择题更新时间:2018-12-15 07:34:22

答案(点此获取答案解析）

证明：设 $\vec{B C} = \vec{a},$

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