Respuesta :

so, the diameter of the cone is 12 cm, therefore its radius is 6 cm, keeping in mind its slant height is 18 cm.


[tex] \bf \textit{surface area of a cone}\\\\
SA=\pi r\stackrel{slant~height}{\sqrt{r^2+h^2}}+\pi r^2~~
\begin{cases}
r=radius\\
-------\\
\qquad ~~ ~~ ~ r=6\\
\sqrt{r^2+h^2}=18
\end{cases}
\\\\\\
SA=\pi (6)(18)+\pi (6)^2\implies SA=108\pi +36\pi \implies SA=144\pi [/tex]

sqdancefan

The base area is given by

... A = π·r²

For a radius of 6 cm, this is

... A = π·(6 cm)² = 36π cm²


The lateral area is given by

... A = (1/2)C·s = (π/2)d·s

where C is the circumference of the base, d is the base diameter, and s is the slant height.

For a base diameter of 12 cm, this is

... A = (π/2)·(12 cm)·(18 cm) = 108π cm²


Then the total surface area of the cone is

... surface area = base area + lateral area

... surface area = (36π cm²) + (108π cm²)

... surface area = 144 cm²

Otras preguntas