Question:
Tick (✓) the correct answer:
The maximum length of a pencil that can be kept in a rectangular box of dimensions 12 cm × 9 cm × 8 cm, is
(a) 13 cm
(b) 17 cm
(c) 18 cm
(d) 19 cm
Solution:
(b) 17
Length of the diagonal of a cuboid $=\sqrt{l^{2}+b^{2}+h^{2}}$
$\therefore \sqrt{l^{2}+b^{2}+h^{2}}=\sqrt{12^{2}+9^{2}+8^{2}}=\sqrt{144+81+64}=\sqrt{289}=17 \mathrm{~cm}$