11.
如图,已知Rt△ABC中,斜边BC上的高AD=3,cosB=$\frac{3}{5}$,则AC的长为( )
| A. | 3 | B. | 3.5 | C. | 4.8 | D. | 5 |
10.有甲、乙两个不透明的袋子中装着只有颜色不同的小球,甲袋中有两个红球,乙袋中有一个红球,一个白球,从两个袋中各摸出一个球,则两个球都是红球的概率是( )
| A. | $\frac{1}{2}$ | B. | $\frac{1}{4}$ | C. | $\frac{2}{3}$ | D. | $\frac{1}{3}$ |
6.方程组$\left\{\begin{array}{l}{x-z=4}\\{z-2y=-1}\\{x+y-z=-1}\end{array}\right.$的解是( )
0 283192 283200 283206 283210 283216 283218 283222 283228 283230 283236 283242 283246 283248 283252 283258 283260 283266 283270 283272 283276 283278 283282 283284 283286 283287 283288 283290 283291 283292 283294 283296 283300 283302 283306 283308 283312 283318 283320 283326 283330 283332 283336 283342 283348 283350 283356 283360 283362 283368 283372 283378 283386 366461
| A. | $\left\{\begin{array}{l}{x=7}\\{y=-5}\\{z=-11}\end{array}\right.$ | B. | $\left\{\begin{array}{l}{x=-7}\\{y=5}\\{z=-11}\end{array}\right.$ | C. | $\left\{\begin{array}{l}{x=-7}\\{y=-5}\\{z=-11}\end{array}\right.$ | D. | $\left\{\begin{array}{l}{x=7}\\{y=-5}\\{z=11}\end{array}\right.$ |