在△ABC中,角A、B、C的对边为a、b、c.已知5bcosA=3acosC+3ccosA
(1)求cosA的值
(2)求
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550016_ST/0.png)
的值.
考点分析:
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设M是
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550015_ST/0.png)
,定义f(M)=(m,n,p),其中m、n、p分别是△MBC,△MCA,△MAB的面积,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550015_ST/1.png)
的最小值是
.
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已知
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550014_ST/0.png)
,且关于x的方程
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550014_ST/1.png)
有实根,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550014_ST/2.png)
与
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550014_ST/3.png)
的夹角的取值范围是
.
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等差数列{a
n}中,a
n>0且2a
3-a
72+2a
11=0,则S
13的值为
.
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已知点A(3,6),B(-3,3),且点C分有向线段
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550012_ST/0.png)
的比为2,则点C的坐标为
.
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已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/0.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/1.png)
满足
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/2.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/3.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/4.png)
(λ,μ∈R),若M为AB的中点,并且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/5.png)
,则点(λ,μ)在( )
A.以(
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/6.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/7.png)
)为圆心,半径为1的圆上
B.以(
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/8.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/9.png)
)为圆心,半径为1的圆上
C.以(
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/10.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/11.png)
)为圆心,半径为1的圆上
D.以(
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/12.png)
,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225040683955083/SYS201311012250406839550011_ST/13.png)
)为圆心,半径为1的圆上
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