Question

the curved surface area of a right circular cylinder and right circular cone standing on the same base and having the same height of 3.5cm are in the ratio 8 :5. find the curved surface area of the cone

Answer 1

Total volume of the two cubes = 2 × 64 cm3

              = 128 cm3

        Let the edge of each cube = x

        ∴ x3 = 64 = 43

        ∴ x = 4 cm

        Now, Length of the resulting cuboid l = 2x cm

              Breadth of the resulting cuboid b = x cm

              Height of the resulting cuboid h = x cm

        ∴ Surface area of the cuboid = 2 (lb + bh + hl) = 2[(2x . x) + (x . x) + (x . 2x)]

              = 2[(2 × 4 × 4) + (4 × 4) + (4 × 2 × 4)] cm2

              = 2 [32 + 16 + 32] cm2 = 2[80] cm2 = 160 cm2

It's is ok