Question

Two identical cubes each of total surface area of $6c{m}^2$ are joined end to end. Which of the following is the total surface area of the cuboid so formed?

• A. $10c{m}^2$
• B. $12m^2$
• C. $12c{m}^2$
• D. $10m^2$

Answer 1

The correct option is A $10c{m}^2$

The total surface area of two cubes $=2\times 6c{m}^2=12c{m}^2$

Area of one face of the cube $=1c{m}^2$
Now, if the two cubes are clubbed together to make a cuboid, then two surfaces will be hidden.

So, total surface area of the cuboid $=12c{m}^2-(2\times 1c{m}^2)$
$=12c{m}^2-2c{m}^2$
$=10c{m}^2$