Meaning of base surface area of a cylinder and hollow cylinder can you show me plz as i did not understand

Dear student,

Assuming your question to be as follows :

A solid generated by the revolution of a rectangular about one of its sides is called a right circular cylinder.

Each of the circular ends on which the cylinder rests is called base.

The surface area of the base of a cylinder = ${\mathrm{\pi r}}^2$ (Area of the circle)
Curved surface area of cylinder = $2\mathrm{\pi rh}$
where radius : r and height : h

A solid bounded by two coaxial cylinders of the same height and different radii is called a Hollow cylinder.
Curved Surface Area of hollow cylinder = $2\mathrm{\pi rh} + 2\mathrm{\pi Rh}$
Area of base = $\mathrm{\pi }({\mathrm{R}}^2 - {\mathrm{r}}^2)$

Regards