7.已知$α∈(-π,-\frac{π}{2}),tanα=\frac{3}{4}$,则$cos(\frac{3π}{2}-α)+2{sin^2}\frac{α}{2}$=( )
| A. | $\frac{6}{5}$ | B. | $\frac{12}{5}$ | C. | 1 | D. | $-\frac{2}{5}$或$\frac{12}{5}$ |
6.若$\overrightarrow{{e}_{1}},\overrightarrow{{e}_{2}}$是两个单位向量,且(2$\overrightarrow{{e}_{1}}$+$\overrightarrow{{e}_{2}}$)⊥(-2$\overrightarrow{{e}_{1}}$+3$\overrightarrow{{e}_{2}}$),则|$\overrightarrow{{e}_{1}}$+2$\overrightarrow{{e}_{2}}$|=( )
| A. | $\sqrt{6}$ | B. | 6 | C. | $\sqrt{2}$ | D. | 2 |
5.给出下面四个函数:①y=cos|2x|;②y=|sinx|;③$y=cos(2x+\frac{π}{4})$;④$y=tan(2x-\frac{π}{3})$.其中最小正周期为π的有( )
| A. | ①②③ | B. | ②③④ | C. | ②③ | D. | ①④ |
4.已知向量$\overrightarrow{AB}$=($\frac{1}{2}$,$\frac{\sqrt{3}}{2}$),$\overrightarrow{BC}$=($\frac{\sqrt{3}}{2}$,$\frac{1}{2}$),则∠ABC=( )
| A. | $\frac{π}{6}$ | B. | $\frac{π}{3}$ | C. | $\frac{2π}{3}$ | D. | $\frac{5π}{6}$ |
3.已知向量$\overrightarrow{a}$=(k,cos$\frac{π}{3}$),向量$\overrightarrow{b}$=(sin$\frac{π}{6}$,tan$\frac{π}{4}$),若$\overrightarrow{a}∥\overrightarrow{b}$,则实数k的值为( )
| A. | $-\frac{1}{4}$ | B. | -1 | C. | $\frac{1}{4}$ | D. | 1 |
2.若向量$\overrightarrow{AB}$=(2,4),$\overrightarrow{BC}$=(-2,2n),$\overrightarrow{AC}$=(m,2),m,n∈R,则m+n的值为( )
| A. | -2 | B. | -1 | C. | 0 | D. | 1 |
20.大于3的正整数x满足$C_{18}^x=C_{18}^{3x-6}$,x=( )
0 240596 240604 240610 240614 240620 240622 240626 240632 240634 240640 240646 240650 240652 240656 240662 240664 240670 240674 240676 240680 240682 240686 240688 240690 240691 240692 240694 240695 240696 240698 240700 240704 240706 240710 240712 240716 240722 240724 240730 240734 240736 240740 240746 240752 240754 240760 240764 240766 240772 240776 240782 240790 266669
| A. | 6 | B. | 4 | C. | 8 | D. | 9 |