1. Std. :- 6th
Sub. :- Mathematics

2. Chapter no. 13
Perimeter

3. “ A perimeter is a path that surrounds an area.”
The word comes from the Greek peri (around) and meter (measure).
The term may be used either for the path or its length - it can be thought of as the length of the outline of a shape.
“The perimeter of a circular area is called its circumference”.
In short Perimeter of a figure is the sum of the lengths of all sides of that figure

4. Perimeter of a Rectangle :- Formula
3 cm
1.5 cm P Q S R
The Perimeter of a rectangle PQRS = Sum of lengths of all sides
=l(PQ)+l(QR)+l(RS)+l(SP) = =
=2 ( length) + 2 ( breadth)

5. Note :- The Perimeter = 2 X length + 2 X breadth of a rectangle
The Perimeter = 2 ( l + b )
of a rectangle
Note :-
If length & breadth of a rectangle are in Centimeters then unit of perimeter of a rectangle is cm
If length & breadth of a rectangle are in Meters then unit of perimeter of a rectangle is m

6. The Perimeter of the rectangular playground is 390 m.
The length of a rectangular playground is 120 m and its breadth is 75 m. Find its perimeter.
Length of a rectangular playground = 120 m
breadth of a rectangular playground =75 m
The Perimeter of a rectangular playground = 2 X length + 2 X breadth
= 2 X X 75 =
= 390
The Perimeter of the rectangular playground is 390 m.

7. Perimeter of a Square Formula :-
Perimeter of a Square = 4 X length
= 4 X l
Ex. : Find the perimeter 0f square whose side
is 12 cm .
Ans. : Perimeter of a Square = 4 X lengths
= 4 X l
= 4 X 12
= 48 cm

8. Perimeter of a Triangle Formula:-
Perimeter of a triangle = a + b + c b a c

9. Example Find the perimeter of triangle whose sides are 10cm,12cm,14cm.
solution:
Given : sides of triangle : a = 10 cm
b = 12cm
c = 14 cm
Perimeter of a triangle = a + b + c =
= 36 cm