5.在锐角三角形ABC中,若sinA=$\frac{\sqrt{2}}{2}$,sinB=$\frac{\sqrt{3}}{2}$,则C=( )
A. | 30° | B. | 45° | C. | 60° | D. | 75° |
2.定义在R上的函数f(x)满足f(x)=(-2-x),当x≥-1时,f(x)=3-2x,若f(x)在区间(λ,λ+1)上有零点,则λ的值为( )
A. | 1或-4 | B. | -1或4 | C. | -1或3 | D. | 1或-3 |
20.若实数x、y满足$\left\{\begin{array}{l}{x-y+5≤0}\\{x≤3}\\{x+y+k≥0}\end{array}\right.$且z=2x+4y的最小值为-14,则常数k的值为( )
A. | 10 | B. | $\frac{19}{3}$ | C. | 4 | D. | 2 |
19.直线x=$\frac{2π}{3}$和x=$\frac{7π}{6}$是函数f(x)=sin(ωx+φ)(ω>0,0<φ<2π)的两条相邻的对称轴,且函数f(x)在区间($\frac{π}{6}$,$\frac{2π}{3}$)上单调递减,则φ的值为( )
0 252564 252572 252578 252582 252588 252590 252594 252600 252602 252608 252614 252618 252620 252624 252630 252632 252638 252642 252644 252648 252650 252654 252656 252658 252659 252660 252662 252663 252664 252666 252668 252672 252674 252678 252680 252684 252690 252692 252698 252702 252704 252708 252714 252720 252722 252728 252732 252734 252740 252744 252750 252758 266669
A. | $\frac{π}{6}$ | B. | $\frac{π}{3}$ | C. | $\frac{5π}{6}$ | D. | $\frac{7π}{6}$ |