Question

the slant height of the frustum of the cone is 4cm and the perimeters of its circular ends are 18cm and 6cm find the curved surface area of the frustum​

Answer 1

Answer:

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Answer 2

➟ Given :-

→ slant height of the frustum of the cone,l = 4cm

→ perimeter of it's circular ends are 18cm and 6cm

➟ To find :-

→ the curved surface area of the frustum

➟ Solution :-

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

→ perimeter of circular end of the frustum

⟹ 2πR = 18

⟹ πR = 9.

→ perimeter of the circular end of the frustum

⟹ 2πr = 6

⟹ πr = 3.

→ Curved surface area of the frustum

⟹ πl(R +r) sq units

⟹ l × (πR + πr)

⟹ 4x (9+ 3) cm²

⟹ 48 cm²

Hence, the curved surface area of the frustum is 48cm²