5.在△ABC中,已知∠A=60°,AB:AC=8:5,面积为10$\sqrt{3}$,则AB=( )
| A. | 8 | B. | 6 | C. | 5 | D. | 10 |
4.
如图,在正方体ABCD-A1B1C1D1中,E,F,G,H分别为AA1,AB,BB1,B1C1的中点,则异面直线EF与GH所成的角等于( )
| A. | 45° | B. | 60° | C. | 90° | D. | 120° |
3.定义在R上的偶函数f(x)满足:对任意的x1,x2∈[0,+∞)(x1≠x2),有$\frac{f({x}_{2})-f({x}_{1})}{{x}_{2}-{x}_{1}}<0$.则( )
| A. | f(3)<f(-2)<f(1) | B. | f(1)<f(-2)<f(3) | C. | f(-2)<f(1)<f(3) | D. | f(3)<f(1)<f(-2) |
2.设集合U={0,1,2,3,4,5},M={0,3,5},N={1,4,5},则M∩(∁UN)=( )
| A. | {5} | B. | {0,3} | C. | {0,2,3,5} | D. | ∅ |
1.已知命题p:?x∈R,2x2+2x+$\frac{1}{2}$<0,命题q:?x0∈R,sinx0-cosx0=$\sqrt{2}$,则下列判断中正确的是( )
| A. | p是真命题 | B. | q是假命题 | C. | ¬p是假命题 | D. | ¬q是假命题 |
20.若对?x∈R,kx2-kx-1<0是真命题,则k的取值范围是( )
| A. | -4≤k≤0 | B. | -4≤k<0 | C. | -4<k≤0 | D. | -4<k<0 |
18.已知F1(-1,0),F2(1,0)是椭圆C的两个焦点,过F2且垂直x轴的直线交C于A,B两点,且|AB|=3,则C的方程为( )
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| A. | $\frac{x^2}{2}$+y2=1 | B. | $\frac{x^2}{3}$+$\frac{y^2}{2}$=1 | C. | $\frac{x^2}{4}$+$\frac{y^2}{3}$=1 | D. | $\frac{x^2}{5}$+$\frac{y^2}{4}$=1 |