Question 2:
The slant height of a frustum of a cone is 4 cm and the perimeters (circumference) of its circular ends are 18 cm and 6 cm. find the curved surface area of the frustum.
Answer:
Perimeter of upper circular end of frustum = 18
2πr1 =18
r1 = 9/π
Perimeter of lower end of frustum = 6 cm
2πr2 = 6
r2 = 3/π
Slant height (l) of frustum = 4
CSA of frustum = π (r1 + r2) l
Therefore, the curved surface area of the frustum is 48 cm2.
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