Area and Perimeter
Perimeter means distance around a figure or curve. We
can only measure perimeter of a closed figure/2 dimensional shape or curve as
movement around a closed figure or curve is possible.
Perimeter of a Square
A square is a closed figure that has 4 sides of equal
length and 4 equal angles of 90 degree.
Perimeter of a square = sum of all sides
OR 4 x side
Perimeter of a Rectangle
A rectangle is a closed figure that has equal opposite
sides and each angle is of 90 degree. The longer side of rectangle is known as length
of the rectangle and shorter side is known as width or breadth of
Perimeter of Rectangle = L + L + B + B
2 X L + 2 X B (i.e. 2L + 2B)
2 (L + B)
(taking 2 common i.e. twice the sum of length and breadth)
Perimeter of a Triangle
A triangle is a plane figure with three straight sides
and three angles.
Perimeter of Triangle = S + S + S
= Sum of
lengths of three sides
Area is the space enclosed by a plane
figure (2 Dimensional shapes).
Area is measured in "square" units.
The area of a plane figure is the number of squares needed to cover it
Area of Square
Area of square is equal to the product of its length
and breadth expressed in square units. But, in case of square length and
breadth are same, we express area by multiplying its side and side.
Area = Side x Side
Area of Rectangle
Area of rectangle is equal to the product of its length
and breadth expressed in square units.
Area = Length x Breadth
Area of Irregular shapes
To calculate the area of irregular figure, first we
have to divide irregular figure into regular recognizable shapes such as
square, rectangle etc. and then add the area of all the shapes.
find the cost of painting or tiling
the area with cost of painting or tiling per sq. unit
Cost of painting or tiling =
area x cost per sq. unit
Find the cost of painting a wall of a length 30 m and breadth 10 m at the rate
of rupees 10 per sq. m.
Solution: Area of wall = l x
b = 30 x 10 = 300 sq. m
Cost of painting = area x cost per sq. m = 300 x 10 = Rs.3000
find the number of bricks or tiles
Find area of wall or floor.
Find area of bricks or tiles
Divide area of wall or floor by area of a brick or a tile
Number of brick or tile =
Area of wall or floor/Area of a tile or a brick
Find the number of bricks to be laid in a square path of side 1 m, if the side
of each square brick is 5 cm.
Solution: 1 m = 100 cm
Area of square path = 100 cm
x 100 cm
Area of brick = 5 cm x 5 cm
Number of bricks required = 100 x 100 / 5 x 5