如图所示,在△ABC中,D、F分别是BC、AC的中点,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/0.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/1.png)
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/2.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/3.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/4.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/5.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/6.png)
.
(1)用
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/7.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/8.png)
表示向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/9.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/10.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/11.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/12.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272010_ST/13.png)
;
(2)求证:B、E、F三点共线.
考点分析:
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设i、j分别是平面直角坐示系Ox,Oy正方向上的单位向量,且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272009_ST/0.png)
=-2i+mj,
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=ni+j,
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=5i-j,若点A、B、C在同一条直线上,且m=2n,求实数m、n的值.
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在平行四边形ABCD中,E和F分别是边CD和BC的中点,若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272008_ST/0.png)
=λ
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272008_ST/1.png)
+μ
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272008_ST/2.png)
,其中λ、μ∈R,则λ+μ=
.
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已知平面上不共线的四点O,A,B,C,若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272007_ST/0.png)
,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272007_ST/1.png)
=
.
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已知四边形ABCD中,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272006_ST/0.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272006_ST/1.png)
,且|
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272006_ST/2.png)
|=|
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272006_ST/3.png)
|,则四边形ABCD的形状是
.
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已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/0.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/1.png)
、
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/2.png)
中任意两个都不共线,并且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/4.png)
与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/5.png)
共线,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/6.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/7.png)
与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/8.png)
共线,那么
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/9.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/10.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/11.png)
等于( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/12.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/13.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123743429527294/SYS201310251237434295272005_ST/14.png)
D.
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