14.科学家在实验中检测出某微生物细胞直径约为0.0000035米,将0.0000035用科学记数法表示为( )
| A. | 3.5×1 0-6 | B. | 3.5×1 06 | C. | 3.5×1 0-5 | D. | 35×1 0-5 |
11.
如图,⊙O是△ABC的外接圆,直径AD与BC相交于点E,连接CD,若⊙O的半径为5,AB=AC=8,DE=3,则EC长为( )
| A. | 4 | B. | $\frac{21}{4}$ | C. | $\frac{2}{3}$ | D. | $\frac{3}{4}$ |
10.已知圆锥的母线长为5,底面半径为3,则圆锥的侧面积为( )
| A. | 15π | B. | 24π | C. | 30π | D. | 39π |
9.
如图,已知△ABC在平面直角坐标系中的位置如图所示,将△ABC先向下平移5个单位,再向左平移2个单位,则平移后C点的坐标是( )
| A. | (5,-2) | B. | (1,-2) | C. | (2,-1) | D. | (2,-2) |
7.当x=-1,y=2时,代数式x-y的值是( )
0 295082 295090 295096 295100 295106 295108 295112 295118 295120 295126 295132 295136 295138 295142 295148 295150 295156 295160 295162 295166 295168 295172 295174 295176 295177 295178 295180 295181 295182 295184 295186 295190 295192 295196 295198 295202 295208 295210 295216 295220 295222 295226 295232 295238 295240 295246 295250 295252 295258 295262 295268 295276 366461
| A. | 1 | B. | -1 | C. | -3 | D. | 2 |