CLASS-9
VOLUME & SURFACE AREA OF THE SOLIDS - TOTAL SURFACE AREA OF CUBOIDS
TOTAL SURFACE AREA OF THE CUBOID -
Cuboid – A rectangular solid bounded by six rectangular plane faces is called a cuboid. A match box, a chalk box, a brick, a block, a book, etc., are all examples of a cuboid. A cuboid has 6 rectangular faces, 12 edges and 8 vertices. Let us considered a cuboid of length = l units, breadth = b units, and height = h units.
Total surface Area of a Cuboid –
The sum of areas of all six faces of a cuboid is known as it’s total surface area
Total surface area of cuboid = 2 (lb + bh + lh) sq. units
Example.) Find the total surface area of a rectangular solid 12 m long, 10 m broad, and 5 m high.
Ans.) As per the formulae, total surface are of the solid =
2 (lb + bh + lh) sq. units
= 2 {(12 X 10) + (10 X 5) + (12 X 5)} m²
= 2 (120 + 50 + 60) m²
= (2 X 230) m²
= 460 m² (Ans.)