Question

Find the total surface area of a cone of radius $\frac{r}{2}$ and slant height $2l$.

Answer 1

Radius of cone $=\frac{r}{2}$

Slant height of cone$=2l$

Total surface area of cone $=\pi rl+\pi r^2,$ where $r$ is the radius of the cone

$=\pi \frac{r}{2}\times 2l+\pi {\left(\frac{r}{2}\right)}^2$

$=\pi rl+\pi \frac{r^2}{4}$.