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AreaAreaContents

1.General2.Shapes3.Quadrilaterals

and Triangles4.Circles and

Sectors5.Composite Areas

Press “ctrl-A”Press “ctrl-A”

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AreaAreaConversions

mmmm22 cmcm22 mm22 haha kmkm22

x 100x 100 x 10x 10 000000 x 10x 10 000000 x 1x 1 00 000000

÷ 100÷ 100 ÷ 10÷ 10 000000 ÷ 10÷ 10 000000÷ 1÷ 1 00 000000

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AreaAreaIntroduction

is the space inside a shape.

We can find the area by counting squares.

11 22 33 44 55 66 77

889910101111121213131414151516161717

1818 1919 2020 2121 2222 2323 2424 2525 2626 2727

2828292930303131323233333434353536363737

3838 3939 4040 4141 4242 4343 4444 4545

45.545.5

4646

46.546.5

4747

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AreaArea4.3 Formula (1/7)

Counting squares is not easy.

We have formulas for the shapes.

Square Rectangle Parallelogram Rhombus

Trapezium Triangle Circle

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AreaArea4.3 Area of Squares (2/7)

A = s2

6.3 m

= 6.32

= 39.69 m2

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AreaArea4.3 Area of Rectangles (3/7)

A = L x B

3.3 m

= 6.4 x 3.3

= 21.12 m2

6.4 m

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AreaArea4.3 Area of Parallelogram (4/7)

A = B x H

5.3 m5.3 m

= 5.3 x 6.4

= 33.92 m2

6.4 m6.4 m

Slanting Parallelogram

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AreaArea4.3 Area of Trapezium (6/7)

A = 0.5 x (a +b) x h

4 m4 m = 0.5 x (3 + 7) x 4

= 20 m2

7 m7 m

3 m3 m

4 m4 m

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AreaArea4.3 Area of Circle (1/5)

rrA = π x r2

3m3m = π x 332

= 28.274 333…

≈ 28.3 m2

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AreaArea4.4 Area of Sector (2/5)

5555oo

3cm3cm

A = x π r2 θ360

= x π x 32

55360

= 4.319 689 899= 4.3 cm2

Find AreaFind Area

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AreaArea4.4 Area of Sector (3/5)

7cm7cm

A = x π r2 θ360

= x π x 72

135360

= 57.726 765 01= 57.7 cm2

135135oo

Find AreaFind Area

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AreaArea4.4 Area of Sector (4/5)

4545oo

rr

A = x π r2 θ360

48 = x π x r2 45360

A=48cmA=48cm22

Find RadiusFind Radius

r2 = x 48 36045π

÷45÷45x360x360÷÷ππ

r = 11.055 812 783= 11.06

cmHintHint

(360÷(45x(360÷(45xππ)x48))x48)

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AreaArea4.4 Area of Sector (5/5)

A = x π r2 θ360

96 = x π x r2 120360

Find RadiusFind Radius

r2 = x96 360120π

÷12÷1200x36x3600÷÷ππ

r = 9.574 614 73

= 9.57 cm

HintHint

(360÷(120x(360÷(120xππ)x96))x96)

rr

120120oo

A=96cmA=96cm22

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AreaArea4.5 Composite Area (1/2)

Compound Areas (Add)A Triangle = 0.5 x b x h

4 m

= 0.5 x 6 x 3= 9 m2

6 m

3 m

PressPress

A Rectangle = L x B= 6 x 4= 24 m2

A Total = A Triangle + A Rectangle = 9 + 24= 33 m2

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AreaArea4.5 Composite Areas (2/2)Compound Areas (Minus)

6 m

10 m

A Large = L x B= 10 x 6= 60 m2

A Total = A Large - A Small = 60 - 10= 50 m2

2 m

5mA Small = L x B

= 5 x 2= 10 m2