An oil funnel of tin sheet consists of a cylindrical portion 10 cm long attached to a frustum of cone. The diameters of the top and bottom of the frustum are 18 cm and 8 cm respecti8vely. If the slant height of the frustum of the cone is 13 cm, find the area of the tin required to make the funnel from the given information in the figure
`(pi=3.14)`

Explanation

Here, radius (r ) of the cylinder = 4 cm height (h) of the cylinder = 10 cm
slant height (l) of the frustum 13 cm
`R_1 and R_2` of the frstum are 9 cm and 4 cm respectively
Tin required to make the funnel = Curved surface area of the cylindrical portion + Curved surface area of the frustum portion
(The curved surface area) of cuylindrical portion
`=2pirh" "...("Formula")`
`=2pixx4xx10cm^2" "...("substituting the given values")" ...(1)`
(the curved surface area) of the frustum portion
`=pi(R_1+R_2)l" "...("Formula")`
`=pi(9+4)xx13" "...("Substituting the given values")`
`=pixx13xx13cm^2" "...(2)`
`therefore` tin required `=2pixx4xx10+pixx13xx13" "...["From (1) and (2)"]`
`=80pi+169pi`
`=pi(80+169)`
`=3.14xx249=781.86cm^2`
The tin required to make the funnel is `781.86 cm^2`