Question

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.

Answer 1

$$\begin{gathered} r=8cm,h=15cm \\ l=\sqrt{8^2+{15}^2}=\sqrt{64+225}=\sqrt{289}=17cm \\ Surfacearea=2\left(\mathrm{\pi rl}\right)=2\times \frac{22}{7}\times 8\times 17=854.85=855{\mathrm{cm}}^2 \end{gathered}$$