1. Angles Revising Basic Angles Naming Angles Calculating Missing angles
Angles in a Triangle
Corresponding Angles
Alternate Angles
17-Feb-19

2. Type of Angles Vertical Horizontal Obtuse Between 90o – 180o Acute
less than 90o
Right - Angle
exactly 90o
Straight Line Angle
exactly 180o
reflex
over 180o less than 360o
17-Feb-19

3. QUESTION TIME! The angle highlighted is: A Acute B Right Angled
C Obtuse
D Straight
E Reflex
17-Feb-19

4. Naming Angles A X B Y C Z Type of angle is acute
Type of angle is obtuse
Name of angle is ∠ ABC
Name of angle is ∠ ZYX
Or ∠ CBA
Or ∠ XYZ
MIDDLE LETTER IS ALWAYS THE VERTEX
ALWAYS 3 CAPITAL LETTERS
17-Feb-19

5. Examples Name & state the type of angle for the shape below:-
∠ PQS is right angled P Q R S
∠ PRS is right angled
∠ PSR is acute
∠ RPS is acute
∠ PSQ is acute
∠ QPS is acute
17-Feb-19

6. QUESTION TIME! Q Which Statement is FALSE? A ∠ PQR is Obtuse
B ∠ QRS is Obtuse
C ∠ STR is Right Angled
D ∠ RST is Acute
E ∠ SRT is Acute P R S T
17-Feb-19

7. Calculate Missing Angles1.
65o 2.
65o
115o
25o
120o
95o 4. 3.
34o
123o
23o
145o
17-Feb-19

8. QUESTION TIME! ? Calculate the missing angle. A 256° B 166° C 104°
D 76°
E 14°
76° ?
17-Feb-19

9. QUESTION TIME! ? The missing angle is 110° TRUE or FALSE? 146° 104°
17-Feb-19

10. Related Angles 55o 115o 35o 65o Two angles making a
straight line add to 180o
(Supplementary angles)
Two angles making a
right angle add to 90o
(Complementary angles)
17-Feb-19

11. QUESTION TIME! Calculate the supplement of 163 °. A 13° B 17° C 73°
D 197°
E 343°
17-Feb-19

12. QUESTION TIME! Calculate the complement of 30 °. A 150° B 120° C 90°
D 60°
E 30°
17-Feb-19

13. Opposite Angles are equal.bº
Opposite Angles are equal.
a=b
c=d c° d°
17-Feb-19

14. Calculate Missing Angles1.
35o 2.
98o
145o
35o
145o
82o
82o
98o 3.
79o
43o
43o
58o
58o
79o
17-Feb-19

15. QUESTION TIME! n m Calculate angles m & n A m=67° & n= 67°
B m=113° & n= 67°
C m=67° & n= 113°
D m=67° & n= 127°
E m=127° & n= 67° n m
67°
17-Feb-19

16. angle sum of any Triangle
To determine the
angle sum of any Triangle
Cut off corners 
Cut off corners 
Cut off corners 
17-Feb-19

17. All angles in a triangle
add up to 180o
180o
17-Feb-19

18. Calculating Missing Angles
Copy out the following triangles and find the missing angles.
61°
50o xo
38o
87o xo xo xo
32o
52°
65°
65°
Remember all the angles add up to 180o
17-Feb-19

19. Calculate the missing angle
QUESTION TIME!
Calculate the missing angle
A 67°
B 76 °
C 77 °
D 113 °
E 114 °
F 247 °
76° ?
37°
17-Feb-19

20. Corresponding Angles
look for
Parallel Lines
shapes
17-Feb-19

21. Corresponding Angles
Which angles are equal?
17-Feb-19

22. Which angles are equal to the shaded angle?
17-Feb-19

23. QUESTION TIME! True or False? The value of x is 131°. x° 131°
17-Feb-19

24. What are the values of the missing angles?
Example
123 57 57
What are the values of the missing angles?
123
17-Feb-19

25. QUESTION TIME! ? The angle marked is:- A 180° B 136 ° C 126° D 124 °
F 34 ° ?
54°
17-Feb-19

26. Alternate Angles
Look for
- Z shapes
= equal angles
17-Feb-19

27. Example
Find the value of a.
35°
35° a
17-Feb-19

28. Find the value of d.
123°
A 180°
B 123°
C 190°
D 57° d
17-Feb-19

29. Example
50 °
Find the value
a and b a
130 ° b
50 °
17-Feb-19

30. Example
135°
Find the value
of a and b. c
45°
45° d
17-Feb-19

31. Find the value of q A 37° B 53° C 143° D 153° E 180 ° F 223 ° q 37°
17-Feb-19

32. Extension Find all the missing angles 124° 56° 56° 124° 124 ° 56 ° 56°
17-Feb-19