Given that, a heap of rice is in the form of a cone.
Height of a heap of rice. i.e., cone (h) = 3.5 m
and diameter of a heap of rice i.e., cone = 9 cm
Radius of a heap of rice i.e., cone (r) `= (9)/(2)m`
So, ” “volume of rice `= (1)/(3) pi xx r^(2)h`
` = (1)/(3) xx (22)/(7) xx (9)/(2) xx (9)/(2) xx 3.5`
`= (6237)/(84) = 74.25 m^(3)`
Now, canvas cloth required to just cover heap of rice
= Surface area of a heap of rice
`= pirl`
`= (22)/(7) xx (9)/(2) xx sqrt(((9)/(2))^(2) + (3.5)^(2))`
`=(11 xx 9)/(7) xx sqrt((81)/(4) + 12.25)`
`= (99)/(7) xxsqrt((130)/(4)) = (99)/(7) xx sqrt(32.5)`
`14.142 xx 5.7`
`= 80.61 m^(2)`
Hence,`80.61 m^(2)` canvas cloth is required to just cover heap.