The total surface area of a hemisphere is $4158 \, cm^2$. Find its diameter in $cm$.

The total surface area of a cone is equal to:

The radius and slant height of a conical vessel are $7 \, cm$ and $25 \, cm$ respectively. What is its capacity in litres?

$A$ hemispherical bowl of radius $18\, cm$ is completely filled with medicine. This medicine is to be filled in cylindrical bottles of radius $2\, cm$ and height $4\, cm$. How many bottles are required to empty the bowl?

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

Find the surface area of a sphere with a diameter of $21\, cm$ (in $cm^2$).