Question

A glass lampshade is in the shape of a right circular cone with radius, r, and slant height, I, as given belowr. = 7.5 inches I = 12.5 inches Which of the following is closest to the surface area of the lampshade? 236 sq. in. o 589 sq. in 0412 sq.in295 sq. in.

Answer 1

we can use this example to solve

we have the value of radious and slant height, then we can replace

$\begin{gathered} SA=\pi rs+\pi r^2 \\ \\ SA=\pi(7.5)(12.5)+\pi(7.5)^2 \\ \\ SA=93.75\pi+56.25\pi \\ SA=150\pi\approx471.23 \end{gathered}$

then the Suface area of the cone is 471.23 square inches and the closest value is C 412sq in