Question

Find the total surface area of the cone. Use the r button on your calculator. altitude = 13 cm, diameter = 11 cm, slant height = 15 cm

Answer 1

In general, the area of a cone is given by the formula below

$\begin{gathered} A=\pi r^2+\pi rl \\ r\rightarrow\text{ radius} \\ l\rightarrow\text{ slant height} \end{gathered}$

Therefore, in our case,

$\begin{gathered} r=\frac{11}{2}=5.5 \\ l=15 \\ \Rightarrow A=\pi *5.5^2+\pi *5.5*15 \\ \Rightarrow A=112.75\pi \end{gathered}$

Rounding to two decimal places,

$\Rightarrow A\approx354.22$

The answer is approximately 354.22 cm^, option D.