题文
正三角形ABC边长为2,设
=2

,

=3

,则

·

=________.

题型:未知 难度:其他题型
答案
-2解析
∵
=

+

=

+


,

=

-

=


-

,∴

·

=(

+


)·(


-

)=


·

+


·

-


·

-

2=

×2×2×

+

×2×2×

+

×2×2×

-22=-2.
考点
据考高分专家说,试题“正三角形ABC边长为2,设=2,=3,则.....”主要考查你对 [向量数量积的含义及几何意义 ]考点的理解。
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