已知,方向上的投影為,則 

A.3 B. C.2 D. 

B

解析試題分析:,為兩向量的夾角。故選B。
考點:數(shù)量積
點評:本題需要理解數(shù)量積的幾何意義:向量 與的數(shù)量積等于向量)的模乘以向量)在向量)方向上的投影)。

練習(xí)冊系列答案
相關(guān)習(xí)題

科目:高中數(shù)學(xué) 來源: 題型:單選題

已知向量,滿足||="2," | |=l,且(+)⊥(),則的夾角為

A. B. C. D.

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

已知,,,點C在內(nèi), ,若=2m+m),則=(    )                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         

A.1B.2C.D.4

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

,且,則向量的夾角為(    )
A.300   B.600    C.1200  D.1500

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

在平行四邊形ABCD中,等于(  )

A. B. C. D.

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

平面向量,,若共線,則的值為(    )

A.B.C.1D.4

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

已知,則向量在向量上的投影為(  )

A. B.3 C.4 D.5

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

在平面直角坐標(biāo)系中,O為坐標(biāo)原點,設(shè)向量,,其中=(3,1),=(1,3).若=λ+μ,且0≤λ≤μ≤1,則C點所有可能的位置區(qū)域用陰影表示正確的是                          (     )

查看答案和解析>>

科目:高中數(shù)學(xué) 來源: 題型:單選題

已知平面向量,且滿足。若,則   (   )

A.有最大值-2 B.z有最小值-2 C.z有最大值-3 D.z有最小值-3 

查看答案和解析>>

同步練習(xí)冊答案