For any cone,$l^{2} = \ldots \ldots \ldots$

The curved surface area of a cylinder is $3960\, cm^{2}$. If its radius is $21\, cm$,find its height in $cm$.

State whether the following statement is True or False and justify your answer: If the radius of a cylinder is doubled and its height is halved,the volume will be doubled.

The total surface area of a cone is equal to:

Find the volume of a sphere of radius $2.1 \, cm$. (in $cm^3$)

Lateral surface area of a cube $= \ldots \ldots \ldots$