Question

Find the surface area of the resulting cuboid when two cubes each with 8 cm edge are joined end to end.
$
  {\text{A}}{\text{. }}1440c{m^2} \\
  {\text{B}}{\text{. }}830c{m^2} \\
  {\text{C}}{\text{. }}640c{m^2} \\
  {\text{D}}{\text{. }}560c{m^2} \\
$

Answer 1

Hint: When two cubes are combined or joined, a structure is formed i.e. cuboid, So use the calculate the surface area of a cuboid as $2(lb + bh + lh)$

Complete step-by-step answer:

As it is given in the question that there are two cubes of 8 cm edge and if these two cubes will join, a cuboid is formed, so the length, breadth and height of the new formed cuboid will change.

Hence,
New length $ = $$(8 + 8) = 16$
New breadth $ = $$8cm$
New height $ = $$8cm$

Hence, the surface area of a cuboid is $2(lb + bh + lh)$ ,

Substitute the values in the formula we get $ = $\[2(16 \times 8 + 8 \times 8 + 16 \times 8) = 2(320) = 640 c{m^2}\].

Note: When this type of question appears first note down the given details. When two cubes join end to end then length will be doubled. So here we have to find the total surface area of the cuboid when two cubes are joined end to end.