Question

The length of the longest rod that can be placed in a room of dimensions (10 m × 10 m × 5 m) is
(a) 15 m
(b) 16 m
(c) $10\sqrt{5}\mathrm{m}$
(d) 12 m

Answer 1

(a) 15 m

Length of longest rod = diagonal of the room
= diagonal of a cuboid
$$\begin{gathered} =\sqrt{l^2+b^2+h^2} \\ =\sqrt{100+100+25}\mathrm{m} \\ =\sqrt{225}\mathrm{m} \\ =15\mathrm{m} \end{gathered}$$