Appendix 1: Properties of Triangles and Angles
Reminder: The angles in a triangle add up to 180.
There are three types of triangle. These are:



Equilateral- which has three equal sides
Isosceles- which has two equal sides
Scalene- all sides are different
Acute angles are less than 90.
Obtuse angles are greater than 90and less than 180.
Reflex angles are greater than 180and less than 360.
A. Different Types of Triangles (Diagrams not drawn to scale)
Identify each triangle and the number of angles that are the same within them.
2.
1.
6 cm
5cm
5cm
4 cm
5 cm
4 cm
3.
4.
7cm
2 cm
3cm
3 cm
5cm
4 cm
B. Identify the missing angles and state whether the angles are acute or
obtuse.
1.
45
90
2.
a
60
60
b
3.
c
4.
70
70
d
90
50
C. Angles on a straight line- Calculate the missing angle (not drawn to scale)
Remember angles
on a straight line
add up to 180
1.
2.
a
30
b
3.
160
4.
c
90
d
5.
6.
10
f
25
e
145
Appendix 3: Example of board work
a
?
?
Appendix 4: Worksheet give to pupils for group work, lesson 2 (Not drawn to
scale)
30
Appendix 5: Homework Sheet for Lesson 2
Objective: To use your knowledge of different types of angles
within calculations
A. Calculate the size of the unknown angles marked ‘a’ and ‘b’, related
to corresponding angles.
1.
2.
57
73
a
b
a
b
3.
4.
55
60
a
a
b
b
B. Calculate the size of the unknown angles marked ‘a’ and ‘b’, related to
alternate angles.
1.
2.
72
69
a
a
b
b
3.
4.
52
53
a
a
b
b
C. Comprehensive examples of identifying angles involving parallel lines
1.
2.
89
d
a
63
115
71
b
c
3.
Remember these examples
involve all types of angles
56
e
69
f