Question

The total surface area of a cube of side a is ______.

• A. $3a^2$
• B. $4a^2$
• C. $6a^2$
• D. $12a^2$

Answer 1

The correct option is C $6a^2$

We know,

• the total surface area of a cuboid of length 'l', breadth 'b' and height 'h' is $2(lb+bh+hl)$.
• a cube is nothing but a cuboid whose length, breadth and height are all equal.

So, if the length of an edge of a cube is 'a', then its surface area will be,
$2\left[\right(a\times a)+(a\times a)+(a\times a\left)\right]$
$i.e.,6a^2$
Therefore, total surface area of a cube of side 'a' is $6a^2$.