Answer :

To work out the total surface area of a cuboid with dimensions 15 cm, 20 cm, and 40 cm, you can follow these steps:

  1. Understand the Formula: The total surface area of a cuboid is given by the formula:
    [

    2(lw + lh + wh)
    ]
    where [tex]l[/tex], [tex]w[/tex], and [tex]h[/tex] are the length, width, and height of the cuboid.

  2. Substitute the Dimensions:

    • Here, [tex]l = 15[/tex] cm, [tex]w = 20[/tex] cm, [tex]h = 40[/tex] cm.
  3. Calculate Each Term:

    • [tex]lw = 15 \times 20 = 300[/tex] square cm.
    • [tex]lh = 15 \times 40 = 600[/tex] square cm.
    • [tex]wh = 20 \times 40 = 800[/tex] square cm.
  4. Add the Areas from Each Pair of Faces:

    • Multiply by 2 for each pair of opposite faces to get the total surface area:
      [tex]2(300 + 600 + 800) = 2 \times 1700 = 3400 \text{ square cm}[/tex]

So, the total surface area of the cuboid is [tex]3400[/tex] square centimeters.