Drawing Triangles

1
Drawing Triangles
MTH 3.16a
1. Using a Protractor
2. Select SAS triangles
3. Select ASA triangles
www.mathsrevision.com
4. Select SSS triangles
2
(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
3
A 180o Protractor
4
1. Look directly down onto the cross point.
2. Always use the protractor in a horizontal
manner as shown below.
?
5
Measuring Angles with a 180o Protractor
50o
67o
6
Measuring Angles with a 180o Protractor
120o
135o
7
Drawing SAS Triangles
Aim of the Lesson
We are learning to construct a triangle given
the length of two sides and the included angle
8
Drawing SAS Triangles
SAS Triangles
Side
Side
Angle
9
Drawing SAS Triangles
Toolkit required
10
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
11
Drawing SAS Triangles
Some practice Teejay Book Page 169 Exercise 1
12
(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
13
Drawing SAS Triangles
Part 2 ASA triangles
14
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.
15
Drawing ASA Triangles
ASA Triangles
Angle
Angle
Side
16
Drawing ASA Triangles
Toolkit required
17
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
18
Drawing ASA Triangles
Some practice Teejay Book Page 171 Exercise 2
19
(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
20
Drawing SSS Triangles
Part 3 SSS triangles
21
Drawing SSS Triangles
Aim of the Lesson
We are learning to construct a triangle given
the length of three sides.
22
Drawing SSS Triangles
SSS Triangles
Side
Side
Side
23
Drawing SSS Triangles
Toolkit required
24
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
25
Drawing SSS Triangles
Some practice Teejay Book Page 173 Exercise 3