Question

the slant height of. frustrum of cone is 4cm and the perimeter of its circular end are 18cm and 6cm. Find the curved surface area of the frustrum​

Answer 1

Step-by-step explanation:

Given:

l = 4 cm

Circumference of a circular end = 18 cm

⇒2πr' =18

⇒π×r' = 18/2

⇒π×r' =9 ➡️(1)

Circumference of other circular end = 6 cm

⇒2πr" =6

⇒πr" = 6/2 =3 ➡️(2)

Adding (1) and (2)

Curved surface area = π (r' + r") l

= (9 + 3) × 4

Curved surface area = 48 cm² (square units)