数学解题网薄膜是0.1豪米厚,薄膜卷直径为30厘米,卷轴外径为8厘米,请解答薄膜长度._数学解答

数学解题网薄膜是0.1豪米厚,薄膜卷直径为30厘米,卷轴外径为8厘米,请解答薄膜长度.

人气：472 ℃　时间：2020-06-21 22:16:16

解答

0.1mm=0.01cm
(30-8)÷(0.01×2)=1100,
薄膜长度=[(8+0.01×2)×π+(8+0.01×2+0.01×2)×π+...+(30)×π]
=[(8+0.01×2)×π+(8+0.01×2+0.01×2)×π+...+(8+0.01×2×1100)×π]
=π[8×1100+0.02×(1+2+...+1100)]
=π[8800+0.02×(1101×1100÷2)]
=π[8800+0.02×(605550)]
=3.14[8800+12111]
=3.14×20911
=65660.54(CM)
=656.61(米)