如图，给定两个平面单位向量 OA→ 和 OB→ ，它们的夹角为120°，点C在以O为圆心的圆弧AB上，且 OC→=xOA→+yOB&#x2192_刷题宝

题干

如图，给定两个平面单位向量 OA→ 和 OB→ ，它们的夹角为120°，点C在以O为圆心的圆弧AB上，且 OC→=xOA→+yOB→ （其中x，y∈R），则满足x+y≥ 2 的概率为（）

A： $\sqrt{2} - 1$

B： $\frac{3}{4}$

C： $\frac{π}{4}$

D： $\frac{π}{2}$

上一题下一题 0.0难度选择题更新时间:2016-01-21 11:11:20

答案(点此获取答案解析）

B

同类题1

下图为某同学绘制的DNA片段示意图，请结合DNA分子结构特点，据图回答：

同类题2

读“六大板块分布示意图”，回答下列问题。

同类题3

根据句意，用括号内所给单词的正确形式填空。（一空一词）

1.They are organizing the____ (thirty-nine) sports meeting of their school.

2.The house____ (it) is very beautiful, but the river near it is much polluted.

3.The boy's dad was ____ (complete ) shocked when he saw that his son was playing with fire.

4.The news and talk shows may not be very exciting, but we can expect ____ (learn) a lot from them.

5.My grandfather's sunny character has a great ____ (influent) on me in my life.

同类题4

Her father _______ in the USA for another year, so that she could work toward her master’s degree.

同类题5

两滴水银相互接近时能自动结合为一滴较大的水银滴，这一事实说明（）

小学学科试题库

初中学科试题库

高中学科试题库