8.将一根半径为5厘米的圆木锯成3段,表面积增加( )平方厘米.
A. | 3.14×52×3 | B. | 3.14×52×6 | C. | 3.14×52×4 | D. | 3.14×5×2×6 |
7.在比例尺是1:8的图纸上,甲、乙两个圆的直径比是2:3,那么甲、乙两个圆的实际的直径比是( )
0 160006 160014 160020 160024 160030 160032 160036 160042 160044 160050 160056 160060 160062 160066 160072 160074 160080 160084 160086 160090 160092 160096 160098 160100 160101 160102 160104 160105 160106 160108 160110 160114 160116 160120 160122 160126 160132 160134 160140 160144 160146 160150 160156 160162 160164 160170 160174 160176 160182 160186 160192 160200 199269
A. | 1:8 | B. | 4:9 | C. | 2:3 | D. | 1:4 |