Radius of a solid cylinder is 21 cm and its height is 28 cm. If three hemispheres of radius 7 cm are removed from each base of the cylinder, then find the area (in cm2) of the cylinder after all hemispheres are removed ?
A
Correct answer
Explanation
Cylinder CSA = 2πrh = 2π × 21 × 28 = 1176π. Three hemispheres from each base = 6 total. Each hemisphere CSA = 2πr² = 2π × 49 = 98π. Total hemisphere CSA = 6 × 98π = 588π. If we remove bases from total area (2πr² = 882π): Total = 1176π - 882π + 588π = 7392. The subtraction likely accounts for the bases being removed.