Tick (✓) the correct answer:
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 $=\sqrt{l^{2}+b^{2}+h^{2}}$

$\therefore \sqrt{l^{2}+b^{2}+h^{2}}=\sqrt{12^{2}+9^{2}+8^{2}}=\sqrt{144+81+64}=\sqrt{289}=17 \mathrm{~cm}$