1 Area Area Contents 1.General 2.Shapes 3.Quadrilaterals and Triangles 4.Circles and Sectors 5.Composite Areas Press “ctrl-A” Press “ctrl-A”
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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