Question

Tick (✓) the correct answer:
The diagonal of a cube is $9\sqrt{3}$ cm long. Its total surface area is
(a) 243 cm²
(b) 486 cm²
(c) 324 cm²
(d) 648 cm²

Answer 1

(b) 486 sq cm

Diagonal $=\sqrt{3}acm=9\sqrt{3}cm$
i.e., a = 9
∴ Total surface area $=6a^2=6\times 81=486c{m}^2$