1. Drawing Triangles 1. Using a Protractor 2. Select SAS triangles
MTH 3.16a
1. Using a Protractor
2. Select SAS triangles
3. Select ASA triangles
4. Select SSS triangles
31-Mar-17
Created by Mr. Lafferty

2. (SAS) Starter Questions
Q1. Convert the percentages to fractions.
(a) 30%
(b) 60%
Q2. Write down all the factors of 16.
Q3. Calculate the missing angles.
80o
Q4. Round the following to 1 decimal place.
(a) 4.549
(b) 6.551
31-Mar-17
Created by Mr. Lafferty

3. A 180o Protractor
Outside scale from o to 180o going in a clockwise direction.
Inside scale from o to 180o going in an anti-clockwise direction.
31-Mar-17

4. You need to be able to measure an angle to the nearest degree
You need to be able to measure an angle to the nearest degree. To help you do this you should always:
1. Look directly down onto the cross point.
2. Always use the protractor in a horizontal manner as shown below. 
31-Mar-17

5. Measuring Angles with a 180o Protractor2
0 on the inside so use inside scale
67o
0 on the outside so use outside scale
31-Mar-17

6. Measuring Angles with a 180o Protractor 120o3
Measuring Angles with a 180o Protractor
120o 4
0 on the inside so use inside scale
135o
0 on the outside so use outside scale
31-Mar-17

7. Drawing SAS Triangles ‘We are learning to construct a triangle given
Aim of the Lesson
‘We are learning to construct a triangle given
the length of two sides
and the included angle’
31-Mar-17
Created by Mr. Lafferty

8. Drawing SAS Triangles SAS Triangles Side Side Angle 31-Mar-17
Created by Mr. Lafferty

9. Drawing SAS Triangles Toolkit required Ruler 2. Protractor
3. Pencil & Paper
31-Mar-17
Created by Mr. Lafferty

10. Drawing SAS Triangles Example : Draw to scale the triangle ABC
with AB = 6cm and angle CAB = 30o and AC = 5cm A
Step 1 Draw line AB=6cm
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
31-Mar-17
Created by Mr. Lafferty

11. Some practice Teejay Book Page 169 Exercise 1 Drawing SAS Triangles
31-Mar-17
Created by Mr. Lafferty

12. (ASA) Starter Questions
Q1. Convert to the 24 hour clock.
(a) 7:25 pm
(b) 6:50 am
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
31-Mar-17
Created by Mr. Lafferty

13. Part 2 : ASA triangles Drawing SAS Triangles 31-Mar-17
Created by Mr. Lafferty

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’.
31-Mar-17
Created by Mr. Lafferty

15. Drawing ASA Triangles ASA Triangles Angle Angle Side 31-Mar-17
Created by Mr. Lafferty

16. Drawing ASA Triangles Toolkit required Ruler 2. Protractor
3. Pencil & Paper
31-Mar-17
Created by Mr. Lafferty

17. Drawing ASA Triangles 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
31-Mar-17
Created by Mr. Lafferty

18. Some practice Teejay Book Page 171 Exercise 2 Drawing ASA Triangles
31-Mar-17
Created by Mr. Lafferty

19. (SSS) Starter Questions
Q1. Convert to the 12 hour clock.
(a) 17:15
(b) 05:40
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
31-Mar-17
Created by Mr. Lafferty

20. Part 3 : SSS triangles Drawing SSS Triangles 31-Mar-17
Created by Mr. Lafferty

21. Drawing SSS Triangles
Aim of the Lesson
‘‘We are learning to construct a triangle given the length of three sides’.
31-Mar-17
Created by Mr. Lafferty

22. Drawing SSS Triangles SSS Triangles Side Side Side 31-Mar-17
Created by Mr. Lafferty

23. Drawing SSS Triangles Toolkit required Ruler 2. Compass
3. Pencil & Paper
31-Mar-17
Created by Mr. Lafferty

24. Drawing SSS Triangles Example : Draw to scale the triangle XYZ
with XY = 3cm and XZ = 5cm and YZ = 4cm X y
Step 1 Draw line XY=3cm Z
Step 2 Use your compass to draw part of a circle centre X radius XZ=5cm
Step 3 Use your compass to draw part of a circle centre Y radius YZ=4cm 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
31-Mar-17
Created by Mr. Lafferty

25. Some practice Teejay Book Page 173 Exercise 3 Drawing SSS Triangles
31-Mar-17
Created by Mr. Lafferty