题目
题型:不详难度:来源:
a |
b |
c |
(1)(
a |
b |
c |
c |
a |
b |
0 |
(2)|
a |
b |
a |
b |
(3)(
b |
c |
a |
a |
c |
b |
c |
(4)(3
a |
b |
a |
b |
a |
b |
其中正确的命题有( )
A.(1)(2) | B.(2)(3) | C.(3)(4) | D.(2)(4) |
答案
a |
b |
c |
c |
c |
a |
b |
b |
b |
c |
a |
b |
c |
c |
a |
b |
0 |
(2)是一个正确命题,由向量的减法法则知,两向量差的模一定小两向量模的差;
(3)是个错误命题,因为[(
b |
c |
a |
a |
c |
b |
c |
b |
c |
a |
c |
a |
c |
b |
c |
b |
c |
a |
a |
c |
b |
c |
(4)是一个正确命题因为(3
a |
b |
a |
b |
a |
b |
综上知(2)(4)是正确命题
故选D
核心考点
试题【设a,b,c是任意的非零向量,且相互不共线,下列命题:(1)(a•b)c-(c•a)b=0,(2)|a|-|b|<|a-b|,(3)(b•c)a-(a•c)b不】;主要考察你对平面向量数量积的运算等知识点的理解。[详细]
举一反三
AB |
CD |
AC |
DB |
AD |
BC |
A.0 | B.
| C.1 | D.无法确定 |
π |
6 |
π |
2 |
3 |
CA |
CB |
CM |
A.1 | B.-1 | C.
| D.-
|
a |
b |
a |
b |
A.(1,1,1) | B.0 | C.-2 | D.(0,0,-2) |
x2 |
2 |
y2 |
b2 |
3 |
PF1 |
PF2 |
A.-12 | B.-2 | C.0 | D.4 |