17.
如图,△ABC的顶点均在⊙O上,若∠A=36°,则∠BOC的度数为( )
| A. | 18° | B. | 36° | C. | 60° | D. | 72° |
16.已知直线a∥b∥c,a与b的距离为5cm,b与c的距离为2cm,则a与c的距离是( )
| A. | 3cm | B. | 7cm | C. | 3cm或7cm | D. | 以上都不对 |
15.化简$\sqrt{27}$+$\sqrt{3}$-$\sqrt{12}$的结果为( )
| A. | 0 | B. | 2 | C. | -2$\sqrt{3}$ | D. | 2$\sqrt{3}$ |
14.如图所示,礼盒上下底面为全等的正六边形,其主视图与左视图均由矩形构成,主视图中大矩形各边长已在图中标出,左视图中包含两全等的矩形,如果用彩色胶带如图包扎礼盒,则所需胶带长度至少为( )

| A. | 320cm | B. | 395.24cm | C. | 431.76cm | D. | 480cm |
12.
如图所示的几何体的主视图是( )
0 285989 285997 286003 286007 286013 286015 286019 286025 286027 286033 286039 286043 286045 286049 286055 286057 286063 286067 286069 286073 286075 286079 286081 286083 286084 286085 286087 286088 286089 286091 286093 286097 286099 286103 286105 286109 286115 286117 286123 286127 286129 286133 286139 286145 286147 286153 286157 286159 286165 286169 286175 286183 366461
| A. | B. | C. | D. |