Gaokao Math Practice Question
5.已知单位向量 $\boldsymbol{a}, \boldsymbol{b}$ 的夹角为 $60^{\circ}$, 则在下列向量中, 与 $\boldsymbol{b}$ 垂直的是（）
- A.$\boldsymbol{a}+2 \boldsymbol{b}$
- B.$2 \boldsymbol{a}+\boldsymbol{b}$
- C.$\boldsymbol{a}-2 \boldsymbol{b}$
- D.$2 \boldsymbol{a}-\boldsymbol{b}$
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