Question

The diagonal of a cube is $9\sqrt{3}$cm long. Its total surface area is

(a) $243c{m}^2$

(b) $486c{m}^2$

(c) $324c{m}^2$

(d) $648c{m}^2$

Answer 1

Diagonal of cube $=9\sqrt{3}cm$

$\therefore$ Side $=\frac{9\sqrt{3}}{\sqrt{3}}=9cm$

$\therefore$ Surface area $=6a^2$

$=6(9{)}^2=6\times 81c{m}^2$

$=486c{m}^2$