Area of a rectangle

Area of composite shapes

Area of a right-angled triangle

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Simple Areas

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Starter QuestionsStarter Questionsw

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2. Calculate 25% of 824

3. What is the name of the shape will this net make.

4. Calculate the value of the missing angle.

34o

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Area of a Area of a RectangleRectangle

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1.1. To be able to state area To be able to state area formula for a rectangle.formula for a rectangle.

1. To come up with a formula

for the area of a rectangle.

2. Use the formula to solve problems.

2.2. Apply formula correctly. Apply formula correctly. (showing working)(showing working)

3.3. Answer containing Answer containing appropriate unitsappropriate units

Problem…

General Jack’s Carpets

Only £5 a square metre!

How much for this one? ?

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3 rows of 6 squares

Problem…

6 square metres

6 square metres

6 square metres

= 3 x 6 = 18 square metres

= 1 square metre

3 m

6 m

1m

1m

How much for 18 square metres?

18 x £5 = £90

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Area of a rectangle

6 = 18 m²

3 m

6 m

3

6

Area = length

x breadth

length

breadth

x 3

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Example 1

11 cm

6 cm

Area = length x breadth

A = l x b

A = 11 x 6

A = 66 cm²

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Find the area of the rectangle

Example 2

12 cm

Area = length x breadth

A = l x b

A = 12 x 12

A = 144 cm²

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Find the area of the square

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Starter QuestionsStarter Questionsw

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2. Calculate 30% of 200

3. What is the name of the shape will this net make.

4. Calculate the value of the missing angle.

123o

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ww

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1.1. Know area of a right-Know area of a right-angled triangle formulaangled triangle formula

1. Use the area of a Use the area of a rectangle formula to rectangle formula to help help us to come up us to come up with a with a formula formula to calculate the to calculate the area of any right-angled area of any right-angled

triangle.triangle.

2.2. Use formula to work out Use formula to work out area of triangle.area of triangle.

3.3. Show all working and Show all working and units.units.

Area of A Right-Angled Triangle

Area of a right-angled triangle

Area of rectangle= l x b = 28 cm²

4 cm

7 cm

= 7 x 4

Area of triangle

= 14 cm²

= ½ x 28

= ½ x Area of rectangle

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Area of triangleShort cut

4 cm

7 cm

Area of triangle = 14 cm²

= ½ x 28

= ½ x 7 x 4

Area Δ = x base x height

½

base

height

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Example 1

10 cm

15 cm

Area Δ=½ x base x height

AΔ =½ x b x h

AΔ = ½ x 15 x 10

AΔ = 75 cm²

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Find the area ofthe triangle

Example 2

12 cm

8 cmArea Δ=½ x base x height

AΔ =½ x b x h

AΔ = ½ x 8 x 12

AΔ = 48 cm²

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Find the area ofthe triangle

Now try worksheetExercise 1

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Area of a right-angled triangle

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Starter Starter QuestionsQuestions

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.com 1. 35.6 + 45.5

2. Calculate 25% of 1000

3. What is the name of the shape will this net make.

4. Calculate the value of the missing angle.

34o

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Area of a Area of a CompositeComposite

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1.1. To be able to use To be able to use knowledge gained so far knowledge gained so far to find the area of more to find the area of more complicated shapes..complicated shapes..

1. To use knowledge to find area of more complicate shapes.

2.2. Show appropriate Show appropriate working.working.

Made up ofSimple shapes

?

Composite shapes

6 cm

10 cm

13 cm?3

cm

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6 cm

6 cm?

10 cm

(1) (2)

Area (1)= l x b = 60 cm²

= 10 x 6

Area (2) = 9 cm² = ½ x 3 x 6

= ½ x b x h

Area of shape= (1) + (2)

= 69 cm²

= 60 + 9

3 cm

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Composite shapes

Example 1 Area (1)= =15 x 8

Area (2) = l x b

l x b

= 120 cm²

=9 x 3= 27 cm²

Area of shape =(1) + (2)

= 120 + 27

= 147 cm²

15cm

11

cm

6cm 3cm

(1)

(2)

?9cm

8cm?

Find the area ofthe shape

Example 2 Area (1)= =20 x 12

Area (2) = l x b

12cm

20cm10cm

6cm

(1)

(2)

l x b

= 240 cm²

=10 x 6= 60 cm²

Area of shape =(1) – (2)

= 240 -60

= 180 cm² Find the area ofthe shape

Now try worksheet Exercise 2

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Composite shapes