Question

what is the formula of total surface area of a hollow cylinder ?

Answer 1

$$\begin{gathered} Totalsurfaceareaofhollowcylinder=2\mathrm{\pi rh}+2\mathrm{\pi Rh}+2\left({\mathrm{\pi R}}^2-{\mathrm{\pi r}}^2\right) \\ \mathrm{Where},\mathrm{R}\mathrm{is}\mathrm{the}\mathrm{radius}\mathrm{of}\mathrm{outer}\mathrm{surface}. \\ \mathrm{And},\mathrm{r}\mathrm{is}\mathrm{the}\mathrm{radius}\mathrm{of}\mathrm{inner}\mathrm{surface}. \end{gathered}$$