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?

Answer 1

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`