Example 28.
a)
cuboid
a = 10 ft, b = 6 ft, c = 12 ft
S=2ab+2bc+2ac=2(ab+bc+ac)=2(10\cdot 6 + 6 \cdot 12 +10\cdot 12)=
=2(60+72+120)=2\cdot 252=504 \ (sq\ ft) . Surface area
,
V=abc=10ft \cdot 6 ft \cdot 12ft = 720 \ (cu\ ft) . Volume
b)
cylinder
d = 8 cm – diameter
h = 16 cm
r=\frac{d}{2}=\frac{8\ cm}{2}=4\ cm
Surface area
S=2\pi {r^2}+2\pi{r}\cdot h=2\pi r(r+h)=2\pi \cdot 4(4+16)=8\pi \cdot 20=80\pi \ (cm^2)
Volume
V=\pi r^2\cdot h=\pi \cdot 4^2\cdot 16 =16\pi\cdot 16=256 \pi \ (cm^3)