Upload
julian-summers
View
222
Download
0
Embed Size (px)
Citation preview
Perimeter Of Shapes.
8cm
2cm
5cm
3cmA1
A2
16m
12m
10m
12cm
7cm A1 A2
What Is Perimeter ?
Perimeter is the distance around a shape. Think of a fence.
For example:
Perimeter = 4 + 9 + 4 + 9 = 26 cm
4cm 4cm
9cm
9cm
Area Of Shapes.
8cm
2cm
5cm
3cmA1
A2
16m
12m
10m
12cm
7cm A1 A2
What Is Area ?
Area is the amount of space inside a shape:
Area Area Area Area Area
Area Area Area Area Area
Area Area Area Area Area
Area Area Area Area Area
Area is measured in square units.
1cm
1cm
A square unit is a square measuring one unit in each direction. For example:
It is written as : 1cm2
1cm2
Area Of A Rectangle.
C
The formula for the area of a rectangle is:
Area = Length x Width or A = LW for short.
Length
Width
Example 1
Calculate the area of the rectangle below:
Solution
A = LW
L = 7 W = 4
A = 7 x 4
A = 28cm2
7cm
4cm(1) (2)
3m
5m
This area is in square metres:
1m
1m
Solution
A = LW
L = 3 W = 5
A = 3 x 5
A = 15m2
Example 3.
Calculate the area of the shape above:
8cm
2cm
5cm
3cm
Solution.
Split the shape up into two rectangles:
A1A2
Calculate the area of A1 and A2.
A1
2
5A2 3
6
Area = A1 + A2
Area = ( 2 x 5) + (6 x 3)
Area = 10 + 18
Area = 28cm2
What Goes In The Box ?Find the area of the shapes below :
(1)
8cm
6cm
4.2m
2.7m
(2)
(3)
17cm
8cm
12cm
5cm
48cm2
11.34m2
141cm2
The Area Of A Triangle.Consider the right angled triangle below:
What shape is the triangle half of ?
Rectangle
8 cm
5cm
What is the area of the rectangle?
Area = BH
Base
Height
The formula for the area of a triangle is:
Area = ½ x Base x Height
A = ½ BH
Calculate the areas of the triangles below:
Example 1
10cm
6cm
Solution.
Area = ½ x base x height
base = 10 cm height = 6cm
Area = ½ x 10 x 6
Area = ½ x 60 = 30cm2
Example 2
6.4m
3.2m
Solution.
Area = ½ x base x height
base = 6.4m height = 3.2m
Area = ½ x 6.4 x 3.2
Area = ½ x 20.48 = 10.24m2
Example 3.
16m
12m
10m
Calculate the area of the shape below: Solution.
Divide the shape into parts:
A1A2
Area = A1 + A2
A1A2
12
10
16-12 =4
10
Area = LW + 1/2 BH
Area = 10 x 12 + ½ x 4 x 10
Area = 120 + 20
Area = 140m2
What Goes In The Box ? Find the area of the shapes below :
(1)
8cm
10cm
(2)
10.2 m
6.3m
(3)
25m
18m
12m
40cm2
32.13m2
258m2
The Area Of A Parallelogram.A Parallelogram is any closed shape which has two sets of parallel sides.
We are now going to find a formula for the area of a parallelogram:
Divide the shape into parts:
bArea = b x h
h
Height and Base have to be perpendicular
Example 1
Calculate the area of the parallelogram below :
16cm
13cm
Solution ( Using the formula).
Area = b x h
b = 16 h =13
Area = 16 x 13
Area = 208 cm2