10.在△ABC中,角A,B,C的对边分别为a,b,c,若(a2+b2-c2)tanC=ab,则角C的值为( )
| A. | $\frac{π}{6}$或$\frac{5π}{6}$ | B. | $\frac{π}{3}$或$\frac{2π}{3}$ | C. | $\frac{π}{6}$ | D. | $\frac{2π}{3}$ |
8.计算sin47°cos17°+cos47°cos107°的结果等于( )
| A. | $-\frac{1}{2}$ | B. | $\frac{{\sqrt{3}}}{2}$ | C. | $\frac{{\sqrt{2}}}{2}$ | D. | $\frac{1}{2}$ |
7.复数i(3-i)的共轭复数是( )
| A. | 1+3i | B. | 1-3i | C. | -1+3i | D. | -1-3i |
6.复数z满足(1+i)z=|$\sqrt{3}$-i|,则$\overline{z}$=( )
| A. | 1+i | B. | 1-i | C. | -1-i | D. | -1+i |
4.已知向量$\overrightarrow{a}$=(2,-1),$\overrightarrow{b}$=(1,7),则下列结论正确的是( )
| A. | $\overrightarrow{a}$⊥$\overrightarrow{b}$ | B. | $\overrightarrow{a}$∥$\overrightarrow{b}$ | C. | $\overrightarrow{a}$⊥($\overrightarrow{a}$+$\overrightarrow{b}$) | D. | $\overrightarrow{a}$⊥($\overrightarrow{a}$-$\overrightarrow{b}$) |
2.袋子中装有大小相同的6个小球,2红4白,现从中有放回的随机摸球3次,每次摸出1个小球,则至少有2次摸出白球的概率为( )
0 228446 228454 228460 228464 228470 228472 228476 228482 228484 228490 228496 228500 228502 228506 228512 228514 228520 228524 228526 228530 228532 228536 228538 228540 228541 228542 228544 228545 228546 228548 228550 228554 228556 228560 228562 228566 228572 228574 228580 228584 228586 228590 228596 228602 228604 228610 228614 228616 228622 228626 228632 228640 266669
| A. | $\frac{20}{27}$ | B. | $\frac{2}{3}$ | C. | $\frac{16}{27}$ | D. | $\frac{7}{9}$ |