Question

Comment on the statement.
The surface area of a cuboid formed by joining face-to-face 3 cubes of side 2a is 3 times the surface area of a cube of side

• A. True
• B. False
• C. Insufficient data

Answer 1

The correct option is B False

False.
Three cubes having side 2a are joined face-to-face, then the cuboid so formed has the same height and breadth as the cubes but its length will be thrice that of the cubes.

Hence, the length, breadth and height of the cuboid so formed are 3(2a), a and a, respectively.

Then, its surface area $=2(lb+bh+hl)$
$=2(6a^2+a^2+6a^2)$
$=2\left(13a^2\right)$
$=26a^2$
Now, the surface area of the cube of side $2a=6(Side{)}^2=6(2a^2)=12a^2$

Hence, the statement is false.