Example-3. A sphere, a cylinder and a cone are of the same radius and same height. Find the ratio of their curved surface areas.
Solution: Let r be the common radius of a sphere, a cone and cylinder.
Height of sphere = its diameter = 2r
Then, the height of the cone = height of cylinder = height of sphere.
= 2r
Example-4. A company wants to manufacture 1000 hemispherical basins from a thin steel sheet. If the radius of each basin is 21 cm., find the area of steel sheet required to manufacture the above hemispherical basins?
Solution: Radius of the hemispherical basin (r) = 21 cm
