Question

We do not understand how to figure this out when part of the cone is missing.

Answer 1

we have that

the surface area of a truncated solid is equal to

`SA=\pi\cdot\lbrack LR+Lr+R^2+r^2\rbrack`

where

L is the slant heigh --------> L=6 cm

R=8 cm

r=4 cm

substitute

`SA=\pi\cdot\lbrack6\cdot8+6\cdot4+8^2+4^2\rbrack`
`\begin{gathered} SA=\pi\cdot\lbrack48+24+64+16\rbrack \\ SA=\pi(152) \\ SA=477.52cm2 \end{gathered}`