Question

the outer radius of a cylinder is 4m and inner radius is 3m and the height of the hollow cylinder is 5m, then its whole surface area will be equal to :

Answer 1

Find the outer curved surface area:

Curved Surface Area = 2πrh

Curved Surface Area = 2π (4)(5) = 40π m²

Find the inner curved surface area:

Curved Surface Area = 2πrh

Curved Surface Area = 2π (3)(5) = 30π m²

Find the top area:

Area = πr²

Area = π (4)² - π (3)² = 7π m²

Find the bottom area:

Area = area of the top area = 7π m²

Find total surface area:

40π + 30π + 7π + 7π = 84π = 264 m²

Answer: The surface area is 264 m²