题文
如图,BC、DE是半径为1的圆O的两条直径,
,则

( )

A.

B.

C.

D.

题型:未知 难度:其他题型
答案
B解析

,r=1,


.故选B.
考点
据考高分专家说,试题“如图,BC、DE是半径为1的圆O的两条直.....”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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