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SCALE DRAWINGS
CHAPTER 9MATHEMATICS
FORM 3
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(1) SKECTH SHAPES
Same size as object
Smaller than the object
Larger than the object
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Same size as object
OBJECT IMAGE
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Smaller than the object
OBJECT
IMAGE
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Larger than the object
OBJECT
IMAGE
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Sketch figure : Same size
OBJECT
IMAGE
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Sketch figure : Smaller size
OBJECT
IMAGE
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Sketch figure : Larger size
OBJECT
IMAGE
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(2) DRAW GEOMETRICALSHAPE USING SCALE
Scale, d = scaled length
actual length
1 = scaled length
n actual length
IMAGE
OBJECT
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Draw the following shape to a scale 1:2
A
B
C
1 = scaled length
n actual length
Find length AB
and AC
1 = AB
2 AB
1 = AB
2 2
1 x 2 = AB
2
AB = 1
BC = 1
1 = AC
2 AC
1 = AC2 4
1 X 4 = AC
2
AC = 2
A
B
C
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Draw the following shape to a scale 1:
A
B
C
1 = scaled length
n actual length
Find length AB
and AC
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NOW , lets try PMR ExamQuestions!!
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(3) SOLVING PROBLEMS
SUPERSCORE book, page 90
Lets try Question (a) and (b)
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TRANSFORMATIONS ll
CHAPTER 10
MATHEMATICS
FORM 3
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(1) SIMILARITY
Same shapes, same size
Same shapes, different size
All the corresponding angles are equal All the corresponding
lengths have thesame ratio.
Corresponding angles
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SIMILAR ?
A
B
CE
D
F
Corresponding angles
Corresponding lengths
M L R ?Corresponding angles
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SIMILAR ?
A
B
CE
D
F
Corresponding angles
Corresponding lengths
10
4
6
15
9
6
BA = 6 = 2
DE 9 3
AC = 4 = 2
EF 6 3
BC = 10 = 2
DF 15 3
P E
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SKILL PRACTICE 10.1a, page 205
AB =
DE
BC =
EF
AC =
DF
2(b)
3 cm
6 cm
4 cm12 cm
6 cm
8 cm
A
BC
D
E
F
LL PR E 10 1 205
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SKILL PRACTICE 10.1a, page 2052(d) 3 cm
8 cm
5 cm 6cm
5
8
3 = 1
6 2
The ratio is
not the same
NOT SIMILAR
K LL PR CT CE 10 1b 207
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SKILL PRACTICE 10.1b, page 2071(a)
7 cm
3 cmx cm
y cm
6 cm
8 cm
x = 3
8 6
x = ?
y = 6
7 3
y = ?
(2) ENLARGEMENT
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(2) ENLARGEMENTScale factor, k
= length of side of image
length of side of object
= distance of a point of image from O
distance of a point of object from O
B
B
A
CC
O is the centre of enlargement
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HOW to find the centre of enlargement ?
0 1 2 3 4 5 6 7 8 9 x
1
9
8
7
6
5
4
3
2
y
We have
found the
centre of
enlargement!
(2, 1)
CHECK YOURSELF
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CHECK YOURSELFCentre of
enlargement, O
= the point of
intersection
CHECK YOURSELF
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CHECK YOURSELFCentre of
enlargement, O
= the point of
intersection
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Scale factor, k= length of side of imagelength of side of
object
= distance of a point of image from O
distance of a point of object from O
IMAGE OF ENLARGEMENT
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IMAGE OF ENLARGEMENTDraw the image with a scale factor using
O
as a centre of enlargement
O
AB
C D
x :1
2
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AREA OF IMAGE
Area of image = k2 x Area of object
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ASSESSMENT
exam-type questions
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THE END
PREPARED BY: SHERLLY SIMUNSubject
Teacherform3@2009_Highlanders
