A circular metal sheet has 4 circular holes of different diameters 20cm,12cm,8cm and 4cm.If the area of the metal sheet is 244π,find its diameter.
Kenneth wants to cut some circular discs of diameter 6 cm from a rectangular iron plate which is 28 cm long and 21 cm wide. He cuts the circular discs in the way as shown in the figure.
i)How many circular discs can he cut?
ii)What percentage of the whole rectangular iron plate will remain?
Area and volume(Plz show step by step)
2008-05-14 5:49 am
回答 (1)
2008-05-14 6:01 am
✔ 最佳答案
1)244π = πr2 -100π-36π-16π-4π
400π=πr2
r2=400
r=20
d=40cm
2) 28/6 = 4.6666666
21/6= 3.5
3x4 =12
he can cut 12 circular discs
[28(21) - 12(π9)]/28(21) x100%
=588-108π/588 x100%
=42.30%
收錄日期: 2021-04-13 15:33:22
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