Curved surface area of a cone $= \dots$

$A$ right triangle with sides $6 \, cm$,$8 \, cm$,and $10 \, cm$ is revolved about the side $8 \, cm$. Find the curved surface area of the solid so formed (in $cm^2$). (in $, cm^2$)

The radius and the slant height of a cone are in the ratio $4: 7$. The ratio of its total surface area to its curved surface area is $\ldots \ldots \ldots$

How many square metres of canvas is required for a conical tent whose height is $3.5 \, m$ and the radius of the base is $12 \, m$ (in $, m^{2}$)?

The total surface area of a cone is equal to:

$A$ metal pipe is $77 \,cm$ long. The inner diameter of a cross section is $4 \,cm$ and the outer diameter is $4.4 \,cm$. Find its outer curved surface area. (in $,cm^{2}$)