本帖最后由 realnumber 于 2018-3-7 17:02 编辑
2017湖州衢州丽水三市高三4月联考
已知O是三角形ABC的外心,∠C=$\frac{\pi}{4}$,若$\vv{OC}=m\vv{OA}+n\vv{OB},(m,n\in R)$,则m+n的取值范围是:
A [$-\sqrt{2},\sqrt{2}$]
B[$-\sqrt{2},1$)
C[$-\sqrt{2},-1$)
D($1,\sqrt{2}$]
RtΔABC中,AB=3,AC=4,BC=5,I是ΔABC的内心,P是ΔIBC内部(不含边界)的动点,
若$\vv{AP}=λ\vv{AB}+μ\vv{AC} (λ,μ\in R)$,则λ+μ的取值范围是
A($\frac{7}{12},1$)B($\frac{1}{3},1$)C($\frac{1}{4},\frac{7}{12}$)D($\frac{1}{4},1$)
BA |