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In a plastic straw, its inner diameter and outer diameter are 5mm and 10mm respectively, and its length is 10cm. Find the volume of the material needed to make the straw. (Give the answer in terms of兀)
ans: 1.875兀cm cube / 1875兀mm cube
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2012-08-01 7:17 am
回答 (1)
2012-08-01 7:33 am
✔ 最佳答案
The volume of the material needed to make the straw = The volume of a cylinder with diameter 10mm - The volume of a cylinder with diameter 5mm
= π(10/2)² 100 - π(5/2)² 100 ........ Tips : 10cm = 100mm = 2500π - 625π= 1875π mm³ or 1875π / 10³ = 1.875 cm³
2012-07-31 23:34:43 補充：
or 1875π / 10³ = 1.875π cm³
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