Perimeter of rectangle :
Here we are going to see how to find the perimeter of rectangle. First let us see the formula and then you can find the example problems based on this formula.
The total length of the lines enclosed by the rectangle is called the perimeter of the rectangle.
Perimeter = 2 (L + B)
Here L stands for length and B stands for breadth. Now let us see some example problems to understand this topic better.
Example 1 :
A rectangle is of length 16 cm and breadth 12 cm. What is the perimeter?
Perimeter of a rectangle = 2 (L + B)
Here Length = 16 cm and Breadth = 12 cm
= 2 ( 16 + 12 ) ==> 56 cm
Hence, the perimeter of the rectangle = 56 cm
Example 2 :
The perimeter of a rectangle is 50 cm. The length is 15 cm. What is the area?
Perimeter of the rectangle = 50 cm
2 (L + B) = 50 ==> L + B = 50/2 ==> 25
Here the length is 15 cm
15 + B = 25 ==> B = 10 cm
Hence, the required breadth is 10 cm
Example 3 :
The area of the rectangle is 150 cm². If the length is twice the width. What is the perimeter?
Let "x" be the width then "2x" be the length of the rectangle.
Area of the rectangle = 150 cm²
L x B = 150 ==> x x 2x = 150 ==> 2x² = 150
x² = 75 ==> x = √75 ==> x = √5 x 5 x 3
x = 5√3
length = x = 5 √3 cm
Breadth = 2x = 2(5 √3) = 10 √3 cm
Therefore length and breadth are 5√3 and 10√3 respectively.
Perimeter of the rectangle = 2 (L + B)
= 2(5 √3 + 10 √3)
= 2 (15 √3)
= 30 √3 cm
Hence, the perimeter of rectangle is 30 √3 cm
Example 4 :
The number of marble slabs of size 20 cm x 30 cm required to pave the floor of a square room of side 3 meters, is:
Number of marble required = Area of square/Area of one marble
Side length of square = 3 m = 3 x 100 = 300 cm
length of marble = 20 cm and breadth = 30 cm
Area of room:
Since the room is in the shape of square, we have to use the formula for area of square.
Area of square shaped room = a² = 300²
Area of one marble:
Here the marble is in the shape of rectangle.
So, Area of one marble = length x breadth
= 20 x 30
Number of marbles required = (300 x 300) / (20 x 30)
Hence, 150 marbles are needed to pave the square shaped room.
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