Formulas of Chapter 13

SURFACE AREA OF A CUBOID:

Let us consider a cuboid of length = 1 units Breadth = b units and height = h units

Then we have :
(i) Total surface area of the cuboid =2(l * b + b * h + h * l) sq. units
(ii) Lateral surface area of the cuboid = [2 (1 + b)* h] sq. units
(iii) Area of four walls of a room = [2 (1 + b)* h] sq. units. = (Perimeter of the base * height) sq. units
(iv) Surface area of four walls and ceiling of a room = lateral surface area of the room + surface area of ceiling =2(1+b)*h+l*b
(v) Diagonal of the cuboid = √l2 + b2 + h2

SURFACE AREA OF A CUBE :

Consider a cube of edge a unit.
(i) The Total surface area of the cube = 6a2 sq. units
(ii) Lateral surface area of the cube = 4a2 sq. units.
(iii) The diagonal of the cube = √3 a units.

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