满分5 >
高中数学试题 >
已知锐角△ABC的内角A,B,C的对边分别为a,b,c,23cos2A+cos2...
已知锐角△ABC的内角A,B,C的对边分别为a,b,c,23cos2A+cos2A=0,a=7,c=6,则b=( )
A.10
B.9
C.8
D.5
考点分析:
相关试题推荐
函数f(x)=(1-cosx)sinx在[-π,π]的图象大致为( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220008_ST/images0.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220008_ST/images1.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220008_ST/images2.png)
D.
查看答案
O为坐标原点,F为抛物线C:y
2=4
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220007_ST/0.png)
x的焦点,P为C上一点,若|PF|=4
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220007_ST/1.png)
,则△POF的面积为( )
A.2
B.2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220007_ST/2.png)
C.2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220007_ST/3.png)
D.4
查看答案
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220006_ST/images0.png)
执行右面的程序框图,如果输入的t∈[-1,3],则输出的s属于( )
A.[-3,4]
B.[-5,2]
C.[-4,3]
D.[-2,5]
查看答案
设首项为1,公比为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124315745722062/SYS201310251243157457220005_ST/0.png)
的等比数列{a
n}的前n项和为S
n,则( )
A.S
n=2a
n-1
B.S
n=3a
n-2
C.S
n=4-3a
nD.S
n=3-2a
n
查看答案
已知命题p:∀x∈R,2
x<3
x;命题q:∃x∈R,x
3=1-x
2,则下列命题中为真命题的是( )
A.p∧q
B.¬p∧q
C.p∧¬q
D.¬p∧¬q
查看答案