RD Sharma Solutions Class 8 Mathematics Solutions for Volume Surface Area Cuboid Cube Exercise 21.3 in Chapter 21 - Volume Surface Area Cuboid Cube

Question 3 Volume Surface Area Cuboid Cube Exercise 21.3

A cuboidal box is 5 cm by 5 cm by 4 cm. Find its surface area.


Given details are,

Dimensions of cuboidal box = 5cm × 5cm × 4cm

We know that,

Surface area of cuboid = 2 (lb + bh + hl) cm2

= 2 (5×5 + 5×4 + 4×5)

= 2 (25 + 20 + 20)

= 2 (65)

= 130 cm2

Video transcript
[Music] hello dear student i am sunita nair from leader learning and i am here to help you with this problem which goes like this it's a simple one so let's do it we have a cuboidal box which is 5 centimeters by five centimeters by four centimeters we are required to find its surface area so i've got a cute box here which uh which kind of resemble the dimensions given five centimeters by five centimeters meaning the base is more or less is is a square and the height is four centimeters right so this is five centimeters this is five centimeters and the height is 4 centimeters so now what is the formula for the total surface area of a cuboidal box let's work that out so the surface area is given by this formula surface area is given by 2 x l into b that is length into breadth plus the breadth into the height plus the length into the height all right so given that the length is equal to 5 centimeters the breadth is also 5 centimeters and the height is given as 4 centimeters so let's substitute these values we have surface area s a is equal to 2 into l into b that is 5 into 5 plus b into h 5 into 4 plus l into h again 5 into 4 square centimeters now this works out to multiplied by five fives are twenty five plus twenty five into four plus one more twenty so this is two multiplied by twenty five plus forty which is equal to 2 multiplied by 65 which is equal to 130 square centimeters so this is our answer the surface area of the given wooden of the cuboidal box of dimensions 5 by 5 by 4 is 130 square centimeters so i hope you understood the solution do visit our channel for more homework solutions and you can subscribe to it for updates as well thank you
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