設

的三個內(nèi)角為A,B,C,向量

若

,則C=( )
練習冊系列答案
相關習題
科目:高中數(shù)學
來源:不詳
題型:解答題
(本小題滿分10分)已知向量

,

,
(I)求與

平行的單位向量

;
(II)設

,若存在

使得

成立,求

的取值范圍。
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:解答題
設
i,
j是平面直角坐標系中
x軸和
y軸正方向上的單位向量,

=4
i-2
j,

=7
i+4
j,

=3
i+6
j,求四邊形
ABCD的面積.
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:單選題
向量

,

的

夾角為

,則稱

◎

為

,

的積,定義

◎


,若

,

,

, 則

◎

等于
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:單選題
若

與

的夾角為60°,|

|=2,(


+

)·(

-2

)=-2,則向量

的模是 ( )
查看答案和解析>>
科目:高中數(shù)學
來源:不詳
題型:單選題
設向量

=" " ( )
查看答案和解析>>