19.已知a-2b+3=0,则代数式5+2b-a的值是( )
| A. | 2 | B. | 4 | C. | 6 | D. | 8 |
13.
如图,平行四边形ABCD绕点A逆时针旋转30°,得到平行四边形AB′C′D′(点B′与点B是对应点,点C′与点C是对应点,点D′与点D是对应点),点B′恰好落在BC边上,则∠C=( )
0 283136 283144 283150 283154 283160 283162 283166 283172 283174 283180 283186 283190 283192 283196 283202 283204 283210 283214 283216 283220 283222 283226 283228 283230 283231 283232 283234 283235 283236 283238 283240 283244 283246 283250 283252 283256 283262 283264 283270 283274 283276 283280 283286 283292 283294 283300 283304 283306 283312 283316 283322 283330 366461
| A. | 105° | B. | 150° | C. | 75° | D. | 30° |