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 $cm^2$)

The Total Surface Area $(TSA)$ of a cylinder is equal to $\ldots \ldots$

Total surface area of a cylinder $= \dots$

The area of the circular base of a hemisphere is $154 \, cm^{2}$. Then,its total surface area is $\ldots \ldots \ldots \, cm^{2}$.

Write 'True' or 'False' and justify your answer:
$A$ solid cone of radius $r$ and height $h$ is placed over a solid cylinder having the same base radius and height as that of the cone. The total surface area of the combined solid is $\pi[\sqrt{r^{2}+h^{2}}+3r+2h]$.