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
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
Perimeter of a Rectangle
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 rectangle.
Perimeter of Rectangle
L + L + B + B
X L + 2 X B (i.e. 2L + 2B)
(L + B) (taking 2 common i.e. twice the sum of length and breadth)
Perimeter of a Triangle
triangle is a plane figure with three straight sides and three angles.
Perimeter of Triangle
S + S + S
Sum of lengths of three sides
is the space enclosed by a plane figure (2 Dimensional shapes).
is measured in "square" units. The area of a plane figure is
the number of squares needed to cover it completely.
Area of Square
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 of Square = Side x Side
Area of Rectangle
of rectangle is equal to the product of its length and breadth expressed in
Area of Rectangle = Length x Breadth
Area of Irregular shapes
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.
To find the cost of
painting or tiling
Step 1: Find
Step 2: Multiply
the area with cost of painting or tiling per sq. unit
Cost of painting or tiling = area x cost per sq. unit
Illustration: 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.
of wall = l x b = 30 x 10 = 300 sq. m
of painting = area x cost per sq. m = 300 x 10 = Rs.3000
To 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
Illustration: 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.
m = 100 cm
of square path = 100 cm x 100 cm
of brick = 5 cm x 5 cm
of bricks required