The radii of the ends of a bucket 30 cm high are 21 cm and 7 cm. Find its capacity in litres and the amount of sheet required to make this bucket.

Explanation

Although we can solve this problem by suing the similar trianlges, but here we are using the direct formula.
Volume of bucket=`(1)/(3)pih(r_(1^(2))+r_(1)r_(2)+r_(2^(2))`
`=(1)/(3)xx(22)/(7)xx30(21^(2)+21xx7+7^(2))`
`=(1)/(3)xx(22)/(7)xx30x637=20020 cm^(3)=(20020)/(1000)lit`
Capacity =20.2 lit
Area of sheeet = C.S.A of bucket +Area of bse
,=`pil(r_(1)+r_(2))+pir_(2)^(2)=pi[l(r_(1)+r_(2))+r_(2)^(2))]`
`=(22)/(7)[33.10^(28)+49]`
3067.32=3067 `cm^(2)` (approx)