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Question
If the slant height of the frustum of a cone is 6 cm and the perimeters of its circular bases are 24 cm and 12 cm respectively. What is the curved surface area of the frustum?
Solution
The parameter of upper base
`=2pir_1`
`2pir_1= 12`
`r_1 = 6/pi cm`
The parameter of lower base
`=2pir_2`
`2pir_2= 24`
`r_2 = 12/pi cm`
The surface area of frustum
`=pi(6/pi + 12/pi) xx 6`
`= pi xx 18/pi xx 6`
`=108 cm^2`
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