Question

derive the volume of sphere

Answer 1

If two solids have cross sections of equal area for all horizontal slices, then the have the same volume.

Therefore the volume of the hemisphere

= volume of cylinder - volume of cone
= (π R3) - (1/3) (π R3)
= (2/3) (π R3)

The volume of the sphere is twice that. 

as 2 complet hemispher makes 1 complet spher

So it is (4/3)(π R3).

Answer 2

If two solids have cross sections of equal area for all horizontal slices, then the have the same volume.

Therefore the volume of the hemisphere

= volume of cylinder - volume of cone
= (π R3) - (1/3) (π R3)
= (2/3) (π R3)

The volume of the sphere is twice that. 

as 2 complet hemispher makes 1 complet spher

So it is (4/3)(π R3).