Question

Surface area of a wooden sphere is 40 cm². It is cut into two identical hemispheres. Find 

a. The area of the plane surface of one of the hemispheres, 

b. Its surface area.

Answer 1

a. Surface area of the sphere = 4 πr²

Here, 4 πr² = 40cm²

πr² = 10cm²

∴ Area of plane surface = πr² = 10cm²

b. Surface area of one piece (hemisphere) = 3 πr² = 3 x 10 = 30cm²