Question

find total surface area of a hemisphere off radius 2 r units

Answer 1

$$\begin{gathered} \mathrm{Let}\mathrm{the}\mathrm{radius}\mathrm{of}\mathrm{the}\mathrm{hemisphere}=\mathrm{R} \\ \mathrm{Now},\mathrm{R}=2\mathrm{r} \\ \mathrm{TSA}\mathrm{of}\mathrm{hemisphere}=3{\mathrm{\pi R}}^2=3\mathrm{\pi }{\left(2\mathrm{r}\right)}^2=3\mathrm{\pi }\times 4{\mathrm{r}}^2=12{\mathrm{\pi r}}^2 \end{gathered}$$