Question

what is the surface area of a cuboid formed by joining two cubes of side a​

Answer 1

Answer:

we have, two cubes of side a.

These two cubes are joined face to face , then the resultant solid figure is a cuboid which has same breadth and height as the joined cubes has length twice of the length of a cube, i.e. l = 2a,b = a and h = a

Thus, the total surface area of cuboid = 2(lb + bh + hl)

= 2(2a × a + a × a + a × 2a)

= 2[2a2 + a2 + 2a2]

= 10a2

Answer 2

The total surface area of a cuboid formed by joining two cubes of side a​ is   10a².

This can be calculated as follows:

• As per the question, the two cubes are joined, therefore, the resultant solid is a cuboid

• In the resultant cuboidal figure, breadth and height will be equal to the cubes.

• But length will be twice the length of a cube.

• Thus, l = 2a, b = a and h = a

• We know that the surface area of cuboid = 2(lb + bh + hl)

      ∴  = 2(2axa + axa + ax2a)

           = 2(2axa + axa + ax2a)

           = 2[2a² + a² + 2a²]

           = 10a²