mensuration ppt

1. AEES DISTANCE LEARNING PROGRAM 2020
CLASS VI
MATHEMATICS
CHAPTER- 10
MENSURATION
MODULE 1 OF 2
PREPARED BY :-
MR. R.S.SINGH
TGT
AECS -3 , MUMBAI

2. There are some plane figures , we think about their regions and
boundaries.
PERIMETER OF A PLANE FIGURE
Perimeter is the distance covered along the boundary forming a
closed figure when we go round the figure once.
There are some examples of perimeter-
1) Fence of a field.
2) A compound wall on all sides of a house.
3) A track to conduct sports.

3. PERIMETER OF A RECTANGLE
Length
Breadth Breadth
Length
There is a rectangle having 2 lengths and 2 breadths.
Perimeter of rectangle = length + breadth + length + breadth
= 2 x length + 2 x breadth
= 2 x ( length + breadth)

4. Example-
A field is 50 metre long and 25 metre wide. Find the perimeter of the
field.
Solution:-
Length of the field = 50 metres
Width of the field = 25 metres
Perimeter of the rectangular field = 2 x (Length + Breadth)
= 2 x (50 metres + 25 metres)
= 2 x 75 metres
= 150 metres
Perimeter of the field is 150 metres.

5. PERIMETER OF SQUARE
Side
Side Side
Side
In a square all sides are equal in length.
Perimeter of a square = Side + Side + Side + Side
= 4 x Side

6. Example-
Find the perimeter of a square park of side 70 metres.
Solution:-
Side of the park = 70 metre
Perimeter of square park = 4 x length of a side
= 4 x 70 metre
= 280 metre
Perimeter of square park is 280 m.

7. TRIANGLE
Triangle is a three sided closed figure. It has three sides, three vertices and
three angles. Sum of all angles of a triangle is 180 degree. It is a two
dimensional figure. It is the smallest polygon. It is one of the basic shapes in
geometry.
Perimeter of triangle = Side + Side + Side

8. PERIMETER OF EQUILATERAL TRIANGLE
It is an equilateral triangle, its all the three sides are equal in length.
Perimeter of equilateral triangle = Side+Side+Side
= 3 x Side

9. Example-
Find the perimeter of an equilateral triangle of side 14 cm.
Solution-
Side of equilateral triangle= 14 cm
Perimeter of an equilateral triangle = 3 x Side
= 3 x 14 cm
= 42 cm
Perimeter of equilateral triangle is 42 cm.

10. Now let us see some examples-
1.Find the perimeter of a rectangular park whose length is 100 m and
breadth 75 m.
Solution-
Length= 100 m Breadth= 75 m
Perimeter = 2 x (length+ Breadth)
= 2 x (100 m + 75 m)
= 2 x (175 m)
= 350 m
Perimeter of rectangular park = 350 m.

11. 2. If the side of an equilateral triangle is 12 cm, then find its perimeter.
Solution
Perimeter of an equilateral triangle= 3 x side
= 3 x 12 cm
= 36 cm
Perimeter of the triangle is 36 cm.
3. Find the perimeter of a square of side 20 cm
Solution-
Perimeter of square = 4 x Side
= 4 x 20 cm
= 80 cm
Perimeter of square is 80 cm.

12. 4. Find the perimeter of a rectangle whose length and breadth are 150 cm
and 1 m respectively.
Solution-
1 m = 100 cm
Perimeter = 2 x (length + breadth)
= 2 x (150 cm + 100 cm)
= 2 x (250 cm)
= 500 cm
Perimeter of the rectangle is 500 cm.

13. 5. Find the cost of fencing a rectangular park at the rate of Rs. 12 per
metre if the length and width of the park are 225 m and 175 m
respectively.
Solution-
Perimeter of rectangular park = 2 x (length + width)
= 2 x (225 m + 175 m)
= 2 x 400 m
= 800 m
Cost of fencing the rectangular park = Rs12 x 800
= Rs. 9600
The cost of fencing the rectangular park is Rs. 9600.