数学题:把一根长30cm,底面半径是8cm的圆木平均锯成4段

  • 时间:2020-06-07 17:53:28
  • 分类:数学世界
  • 阅读:83 次

数学题:把一根长30cm,底面半径是8cm的圆木平均锯成4段,每段仍是圆柱体,锯成后的表面积比原来增加多少平方分米(得数保留两位小数)

数学题解答:先弄清一个问题:锯成四段,需要锯几次?

答案是3次。而每锯一次,就会多出2个底面,所以一个多出6个底面。3×2=6(个)

增加的表面积,就是用一个底面积去乘6,算式为:3.14 × 82 × 6 = 1205.76(平方厘米)=12.0576(平方分米)≈12.06(平方分米)

答:锯成后的表面积比原来增加12.06平方分米。

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