Sainik School- Mathematics- Revison Area and Perimeter By Sainik Academy
24 November 2014
Area and Perimeter of Squares and Rectangles
Definition: - 
A 4-sided flat shape with straight
sides where:
• all sides have equal length, and
• every interior angle is a right angle (90°)
It is a Quadrilateral and a Regular Polygon
• all sides have equal length, and
• every interior angle is a right angle (90°)
It is a Quadrilateral and a Regular Polygon
Also opposite sides are parallel and of equal length.
Formulae of Area and Perimeter
Difference between a square and a Rectangle
Solved Examples
Formulae –
Square – side x side (Area) Perimeter – 4 x Sides
If Area is given to find the side = √ Area
If Perimeter is given to
find the Side = (Perimeter /4)
Rectangle:-
Rectangle – Length x Breadth (Area),
Perimeter – 2 (Length + Breadth)
Area is always in Square Units
Perimeter is in Basic units
If Area is given to find the Breadth =
area / Length
If Area is given to find the Length = Area / Breadth
If Perimeter is given to find the Length
= (Perimeter /2) – Breadth
If Perimeter is given to find the Breadth = (Perimeter
/2) – Length
Example: 1. Find the area of a square whose one
side is 10 cm
|
Step 1
Given
|
One side of a square is 10 cm
|
|
Step 2
|
|
|
To find
|
Area of the Square
|
|
Step 3
Formulae to be used
|
Side
x Side
( Note for area it is square units and
for Perimeter it is just Units)
|
|
Step 4
Working
|
10 x 10 = 100( Now add Units to this
answer) square cm
|
|
Step 5
Answer
|
Therefore
area of the square is 100 sq cm
|
2. Find the Perimeter of a square whose one side is 8 m
|
Step 1
Given
|
One side of a square is 8 cm
|
|
Step 2
|
|
|
To find
|
Area of the Perimeter
( Note for area it is square units and
for Perimeter it is just Units)
|
|
Step 3
Formulae to be used
|
4
x Side
|
|
Step 4
Working
|
8 x4 = 32( Now add Units to this
answer) m ( Note for area it is square units and for Perimeter it is just Units)
|
|
Step 5
Answer
|
Therefore
Perimeter of the square whose one side is 8 m is 32 m
|
3. Area of a
Rectangle whose L = 6 cm and B = 4 cm =
L x B = 24 sq cm
4. Perimeter
of a Rectangle whose L= 8 and B = 6 = 2 (L+B)
= 2 x (8+6) = 2 x (14) = 28 cm
5. Area of a
rectangle is 24 sq cm. it’s L = 6, find the B = Area / L = B = 24/ 6 = 4 cm
6. Perimeter
of a Rectangle is 28 cm, its breadth= 6 cm, find its Length = (P/2) – B = 28/2 = 14-6 = 8 cm
7. Find the
cost of Painting the floor, whose L= 10 m and B = 8m, and cost of painting one
sq m is Rs. 10.
|
Step 1 : Given
|
Length of the rectangle is 10m, Breadth
is 8m. cost of painting the floor per square m is Rs. 10
|
|
Step 2 : To
find
|
1.Area of the Rectangle
2. Cost of painting the Area
( Note for area it is square units and
for Perimeter it is just Units)
|
|
Step 3 : Formulae
used
|
Length
x Breadth
|
|
Step 4 : Working
|
10 x 8 = 80 sq m ( Note for area it is square units
Cost of Painting is Rs. 10 per square
meter ( To find the cost of 80 sq m multiply 80 x 10 = Rs. 800
|
|
Step 5 : Answer
|
Therefore
Cost of Painting the Floor of the Rectangle is Rs. 800
|
8. Find the
cost of fencing a square garden whose one side is 20m, if the cost of fencing
per m is Rs. 10.
Perimeter of
the square garden is given by the formulae 4 x sides = (4 x 20 = 80m)
Hence cost of fencing the square
garden would be = 80 x10 = Rs. 800
For Reqular class room coaching
call 094437 20076
www.sainikrimc.com
for study kit
Comments
Post a Comment