8.函数y=$\sqrt{-{x^2}+4x-3}$的定义域是( )
| A. | (-∞,1] | B. | [3,+∞) | C. | [1,3] | D. | (-∞,1]∪[3,+∞) |
3.曲线y=x3-2x在点(1,-1)处的切线倾斜角为( )
| A. | 30° | B. | 45° | C. | 60° | D. | 135° |
2.
如图,正方形ABCD与正方形BCEF所成角的二面角的平面角的大小是$\frac{π}{4}$,PQ是正方形BDEF所在平面内的一条动直线,则直线BD与PQ所成角的取值范围是( )
0 226660 226668 226674 226678 226684 226686 226690 226696 226698 226704 226710 226714 226716 226720 226726 226728 226734 226738 226740 226744 226746 226750 226752 226754 226755 226756 226758 226759 226760 226762 226764 226768 226770 226774 226776 226780 226786 226788 226794 226798 226800 226804 226810 226816 226818 226824 226828 226830 226836 226840 226846 226854 266669
| A. | [$\frac{π}{4}$,$\frac{π}{2}$] | B. | [$\frac{π}{6}$,$\frac{π}{2}$] | C. | [$\frac{π}{6}$,$\frac{π}{3}$] | D. | [$\frac{π}{3}$,$\frac{π}{2}$] |