Question:
Find the length of the longest pole that can be put in a room of dimensions (10 m × 10 m × 5 m).
Solution:
Length of the longest pole = length of the diagonal of the room
$=\sqrt{l^{2}+b^{2}+h^{2}} \mathrm{~m}$
$=\sqrt{10^{2}+10^{2}+5^{2}} \mathrm{~m}$
$=\sqrt{100+100+25}$
$=\sqrt{225}=15 \mathrm{~m}$