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The slant height of the frustum of a ...

The slant height of the frustum of a cone is 4 cm and the perimeters of its circular ends are 18 cm and 6 cm. Find the curved surface of the frustum.

Text Solution

Verified by Experts

Let the radii of its circular ends be R cm and r cm, and slant height be l cm. Then,

`2piR=18rArrpiR=9`
`2pir=6rArrpir=3.`
`"Also, l = 4cm (given)"`
Curved surface area of the frustum
`=pil(R+r)" sq units"`
`=lxx(piRxxpir)=4xx(9+3)cm^(2)=48cm^(2)`.
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