13.如果3a+2b=1,且3a+2b-c=0,则c的值为( )
| A. | -1 | B. | 1 | C. | 0 | D. | 2 |
12.
如图,在平面直角坐标系中,直线OA过点(2,1),则sinα的值是( )
| A. | $\sqrt{5}$ | B. | $\frac{{\sqrt{5}}}{5}$ | C. | $\frac{1}{2}$ | D. | 2 |
11.在实数-2,0,3,$\sqrt{3}$中,最大的实数是( )
| A. | -2 | B. | 0 | C. | 3 | D. | $\sqrt{3}$ |
10.
如图,AB是⊙O的直径,⊙O交BC的中点于D,DE⊥AC于E连接AD,则下列结论正确的个数是( )
①AD⊥BC;②∠EDA=∠B;③OA=0.5AC;④DE是⊙O的切线.
0 282196 282204 282210 282214 282220 282222 282226 282232 282234 282240 282246 282250 282252 282256 282262 282264 282270 282274 282276 282280 282282 282286 282288 282290 282291 282292 282294 282295 282296 282298 282300 282304 282306 282310 282312 282316 282322 282324 282330 282334 282336 282340 282346 282352 282354 282360 282364 282366 282372 282376 282382 282390 366461
①AD⊥BC;②∠EDA=∠B;③OA=0.5AC;④DE是⊙O的切线.
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |