Question

If LSA of a cube is 100 cm${}^2$, then its side is:

• A. 5 cm
• B. 10 cm
• C. 25 cm
• D. 6 cm

Answer 1

The correct option is A 5 cm

$\text{LSA of a cube}=4a^2,\text{where 'a' is the side of the cube.}$

$\text{Given, LSA}=100{\text{cm}}^2\text{Then,}4a^2=100{\text{cm}}^2\Rightarrow a^2=25{\text{cm}}^2\Rightarrow a=\sqrt{25}\text{cm}\therefore a=5\text{cm}$
(Length is always positive. Hence $\sqrt{25}=-5$ is not considered)