Drawing%20Triangles

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Drawing Triangles
MTH 3.16a
1. Using a Protractor
2. Select SAS triangles
3. Select ASA triangles
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4. Select SSS triangles
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(SAS) Starter Questions
Q1. Convert the percentages to fractions.
(a) 30
(b) 60
Q2. Write down all the factors of 16.
Q4. Round the following to 1 decimal place.
(a) 4.549
(b) 6.551
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A 180o Protractor
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1. Look directly down onto the cross point.
2. Always use the protractor in a horizontal
manner as shown below.
?
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Measuring Angles with a 180o Protractor
50o
67o
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Measuring Angles with a 180o Protractor
120o
135o
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Drawing SAS Triangles
Aim of the Lesson
We are learning to construct a triangle given
the length of two sides and the included angle
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Drawing SAS Triangles
SAS Triangles
Side
Side
Angle
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Drawing SAS Triangles
Toolkit required
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Drawing SAS Triangles
C
30o
B
Example Draw to scale the triangle ABC with
AB 6cm and angle CAB 30o and AC 5cm
A
Step 1 Draw line AB6cm
Step 2 Measure angle CAB from A
C
X
Step 3 Draw the line AC 5cm through X. Label
it C.
A
B
Step 4 Join C to B.
Check angles add to 180o
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Drawing SAS Triangles
Some practice Teejay Book Page 169 Exercise 1
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(ASA) Starter Questions
Q1. Convert to the 24 hour clock.
(b) 650 am
(a) 725 pm
Q2. Write down lowest common multiple of 3, 4 , 5.
Q3. List the first 4 prime numbers.
Q4. Round the following to nearest 1000.
(a) 12,501
(b) 369,765
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Drawing SAS Triangles
Part 2 ASA triangles
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Drawing ASA Triangles
Aim of the Lesson
We are learning to construct a triangle given
two angles and the length of the side in
between.
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Drawing ASA Triangles
ASA Triangles
Angle
Angle
Side
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Drawing ASA Triangles
Toolkit required
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Drawing ASA Triangles
R
Q
Example Draw to scale the triangle PQR with
PQ 8cm and angle RPQ 30o and RQP 40o
P
Step 1 Draw line PQ
Step 2 Measure Angle RPQ from P
R
Step 3 Measure angle RQP from Q
Q
P
Step 4 Intersection point is R
Check angles add to 180o
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Drawing ASA Triangles
Some practice Teejay Book Page 171 Exercise 2
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(SSS) Starter Questions
Q1. Convert to the 12 hour clock.
(b) 0540
(a) 1715
Q2. Write down lowest common multiple of 3, 4 , 5.
Q3. List the prime numbers between 10 and 20.
Q4. Round the following to nearest 100.
(a) 13,551
(b) 369,449
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Drawing SSS Triangles
Part 3 SSS triangles
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Drawing SSS Triangles
Aim of the Lesson
We are learning to construct a triangle given
the length of three sides.
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Drawing SSS Triangles
SSS Triangles
Side
Side
Side
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Drawing SSS Triangles
Toolkit required
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Drawing SSS Triangles
Z
X
Example Draw to scale the triangle XYZ with
XY 3cm and XZ 5cm and YZ 4cm
y
Step 1 Draw line XY3cm
Z
Step 2 Use your compass to draw part of a
circle centre X radius XZ5cm
Step 3 Use your compass to draw part of a circle
centre Y radius YZ4cm
X
Y
Step 4 Intersection point is labelled Z
Step 5 Draw in line XZ and YZ to complete triangle
Check angles add to 180o
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Drawing SSS Triangles
Some practice Teejay Book Page 173 Exercise 3