Question

Find the total surface area of a cone, if its slant height is $21\mathrm{m}$ and diameter of its base is $24\mathrm{m}$. (Assume $\mathrm{\pi }=\frac{22}{7}$)

Answer 1

Finding total surface area of cone

Given, Slant height, $l=21\mathrm{m}$

Diameter, $d=24\mathrm{m}$

Radius, $r=\frac{d}{2}=\frac{24}{2}=12\mathrm{m}$

Total surface area of a cone is given as,

$$\begin{gathered} TSA=\mathrm{\pi r}(\mathrm{l}+\mathrm{r}) \\ \Rightarrow TSA=\frac{22}{7}\times 12\times (21+12) \\ \Rightarrow TSA=1244.57{\mathrm{m}}^2 \end{gathered}$$

Therefore, the total surface area of the given cone is $1244.57{\mathrm{m}}^2$