The radii of a frustum of a cone are $10\,cm$ and $7\,cm$. If its height is $4\,cm$, then its curved surface area is $\ldots \ldots \ldots \,cm^2$. (in $\pi$)

The base of a cone is in the shape of a ..............

Two cones with the same base radius $8\, cm$ and height $15\, cm$ are joined together along their bases. Find the surface area of the shape so formed. (in $cm^2$)

Write 'True' or 'False' and justify your answer:
An open metallic bucket is in the shape of a frustum of a cone,mounted on a hollow cylindrical base made of the same metallic sheet. The surface area of the metallic sheet used is equal to curved surface area of frustum of a cone + area of circular base + curved surface area of cylinder.

In a right circular cone,the cross-section made by a plane parallel to the base is a

$A$ cylinder is closed at both the ends by hemispheres. The radius of the cylinder is $7 \, cm$ and the total height of the article is $34 \, cm$. Find the total surface area of the article. (in $cm^2$)