16.若不等式组$\left\{\begin{array}{l}{x>1}\\{x<a}\end{array}\right.$无解,则a的取值范围是( )
| A. | a>1 | B. | a≥1 | C. | a<1 | D. | a≤1 |
15.
将一副三角板中的两个直角三角板如图放置,使点A在DE上,BC∥DE,其中∠B=∠ACB=45°,∠D=60°,则∠ACE的度数为( )
| A. | 10° | B. | 15° | C. | 20° | D. | 30° |
14.
如图,将一副三角板叠放在一起,使直角的顶点重合于点O,AB∥OC,CD与OA交于点E,已知∠A=30°,则∠DEO的度数为( )
0 298118 298126 298132 298136 298142 298144 298148 298154 298156 298162 298168 298172 298174 298178 298184 298186 298192 298196 298198 298202 298204 298208 298210 298212 298213 298214 298216 298217 298218 298220 298222 298226 298228 298232 298234 298238 298244 298246 298252 298256 298258 298262 298268 298274 298276 298282 298286 298288 298294 298298 298304 298312 366461
| A. | 45° | B. | 60° | C. | 70° | D. | 75° |