15.将角α的终边顺时针旋转$\frac{π}{2}$,则它与以原点为圆心,1为半径的单位圆的交点的坐标是( )
| A. | (cosα,sinα) | B. | (cosα,-sinα) | C. | (sinα,-cosα) | D. | (sinα,cosα) |
14.过两点A(4,y),B(2,-3)的直线的倾斜角为45°,则y=( )
| A. | -$\frac{\sqrt{3}}{2}$ | B. | $\frac{\sqrt{3}}{2}$ | C. | -1 | D. | 1 |
12.已知函数f(x)=x2+ax+4,若对任意的x∈(0,2],f(x)≤6恒成立,则实数a的最大值为( )
| A. | -1 | B. | 1 | C. | -2 | D. | 2 |
10.设a=sin$\frac{13π}{5}$,$b=cos(-\frac{2π}{5})$,c=tan$\frac{7π}{5}$,则( )
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| A. | b<a<c | B. | b<c<a | C. | a<b<c | D. | a<c<b |