1. Finding the missing side of a shape

2. Example 1: The perimeter of a rectangle is 36 m. Find the length if the
breadth is 10 m.
b=10m
p=36
l=?
Solution:
Given:
Breadth(b) = 10 m and Perimeter (p)= 36 m
To find: Breadth of a rectangle
Perimeter of the rectangle = 2 x (length + breadth)
= 2 x (length + 10)
2 x (length + 10) = 36
length + 10 =
Length = 18
Length = 18 – 10 = 8 m
(Transposing 2 to the RHS)
Ans: Length = 8m

3. a=? Example 2: Find the sides of a square if its perimeter is 20 cm?
Solution:
Given: Perimeter of a square(p) = 20 cm
To find: Side of a square(a)
Perimeter of the square = 4 x a
20 = 4 x a
4 x a = 20
a =
a = 5 cm
p=20
a=?
Ans: Side = 5 cm

4. To find length, formula is
Example 3: The area of a rectangular garden is 3600 sq.m. Find the breadth of
the garden if its 60 m long.
Solution:
Given: Length = 60 m and Area = 3600 sq.m
To find: Breadth of a rectangle
Area of the rectangle = length x breadth
Breadth = =
b=?
A=3600
l=60m
Tip:
To find length, formula is
Length =
= 60 m
Ans: Breadth = 60 m

5. By heart this repeating number till 20
Example 4:The area of a square plot is 400 sq.cm. Find the side of
the square plot.
A=400
a=?
Solution:
Given: Area = 400 sq.cm
To find: Side of the square
Area of the square = s x s
400 sq.cm = s x s
400 sq.cm = 20 x 20
s = 20 cm
Tip:
To find sides, remember
2 x 2 = 4
3 x 3 = 9
4 x 4 = 16
5 x 5 = 25…..
By heart this repeating number till 20
Ans: side = 20 m

6. Try these Find the side of a square whose perimeter is 24 cm
The area of a rectangle is 300 m2. Find the breadth whose length is 6m.