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Perameter AND area class 7
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The distance around the outside of a
shape is called its perimeter.
8 cm
6 cm
8 cm
6 cm
The perimeter of the shape is 8 + 6 + 8 + 6 = 28cm.
First we need to find the length of each side by counting the squares.
( Each box stands for 1 cm)
What is the perimeter of each of these shapes?
20 cm18cm
20 cm
22 cm
26cm
Now find the perimeter of these shapes. They are
not drawn to scale.
3cm
3cm
3cm
3cm
3cm
3cm
5cm
7cm7cm
3cm
4cm 4cm
4cm 4cm
3cm 3cm
3cm3cm
Perimeter = 18cm Perimeter = 22cm Perimeter = 28cm
The area of a shape is the
amount of space inside it.
The area of the shape is 18cm2.
To find out how much shape is inside we cancount the squares.
What is the area of each of these
shapes?
12cm2
22cm2
26cm2
To find the area ofan irregular shape you first count the full squares inside
it.
This is an irregular shape. This
means that the sides aren’t
straight.
You then count all the other squares which have more than half the area
covered.
The area of the shape is 60cm2.
What is the area of each of these
shapes?
24cm225cm2
22cm2
35cm2
Counting each square can take a long time. Does anyone know a quicker way?
The area of the shape is 48cm2.
The rectangle is made of 6 rows of 8 squares.
To work out the number of squareswe times 6 by 8.
What is the area of each of these
shapes?
20cm2 18cm2
14cm2
30cm2
22cm2
We can work out the area of a rectanglewithout the grid.
length
wid
thArea = length x width
Now work out the area of these rectangles.
They are not drawn to scale.
36cm235cm2
20cm2
25cm24cm
9cm
7cm
5cm
5cm
4cm
2cm
12.5cm
A shape that is made from other shapes is known as a composite
shape.
To find the area of this shape we
have to split it up into two
rectangles.
10cm
8cm
8cm
2cm
4cm
4cmArea =4 x 10
40cm2
Area =4 x 8
32cm2
Total area = 40 + 32 = 72 cm2
Find the area and perimeter of each of these shapes?
9cm
5cm
5cm
2cm
4cm
5cm
4cm
2cm
11cm
7cm
4cm
3cm 3cm
3cm
7cm
6cm
6cm
11cm
2cm
4cm
5cm
4cm
9cm
5cm
5cm
2cm
4cm
5cm
4cm
2cm
Area =5 x 9
45cm2
Area =4 x 5
20cm2
Total area = 45 + 20 = 65 cm2
Perimeter = 36 cm
6cm
6cm
11cm
2cm
4cm
5cmArea =2 x 5
10cm2 Area =6 x 6
36cm2
Total area = 10 + 36 = 46 cm2
Perimeter = 34 cm
11cm
7cm
4cm
3cm 3cm
3cm
7cm
Total area = 28 + 16 + 21 = 65 cm2
Perimeter = 42 cm
Area =4 x 7
Area =4 x 4
4cmArea =3 x 7
21cm2
28cm2 16cm2
There is another way of
doing this question.
11cm
7cm
4cm
3cm 3cm
3cm
7cm
Total area = 77 – 12 = 65 cm2
Perimeter = 42 cm
Area =7 x 11
Area =3 x 4
4cm
77cm2
12cm2
LET US SOLVE THE FOLLOWING PROBLEM….
FAMILY A FAMILY B
The perimeter of Family A’s pool is 12 units long.
Family B
Family A
The perimeter of Family B’s pool is 14 units long.
Therefore, Family B has more side panels of the pool to clean.
Now look at those same two pools. Which family has more side panels of the pool to clean?
The area of Family A’s pool is?
Family A
Family B
8 square units.
7 square unitsThe area of Family B’s pool is?
Therefore, Family A has the pool with the bigger swimming area.
THANK YOU
