Parallel Lines
In this activity you will investigate the angle properties of parallel lines.
You will need a ruler and protractor.
Part A: Parallel lines
On the worksheet provided:
1. Rule a line that crosses both parallel lines.
This line is called a transversal
2. Label each angle as follows:
a
b
d
c
f
e
h
g
Part B: Investigating angles
1. Copy the following into your workbook
Angle
a
b
c
d
e
f
g
Type of angle
Opposite angle
Corresponding angle
c
e
Size of angle
2. Describe each angle as either acute or obtuse. Write this in your table (Type of angle).
3. Angle a is vertically opposite angle c. In the table (Opposite angle), write the angle which vertically opposite
each angle.
4. Angles a and e are described as corresponding angles as they are in the same position. That is they are both
above the parallel line and on the same side of the transversal. In the table (Corresponding angle), write the
angle which corresponding each angle.
5. Using a protractor, accurately measure each angle. Write your answer in the table (Size of angle).
Part C: Thinking about it
Answer the following questions:
1.
2.
3.
4.
5.
Which angles are equal to angle a?
Which angles are equal to angle b?
What can you say about vertically opposite angles?
What can you say about corresponding angles?
Angles a and b are adjacent angles (next to each other). They are said to be supplementary angles as they
add up to a straight line or 180o. Which other adjacent angles are also supplementary?
6. Angles d and e are described as co-interior angles. Which other pair of angles could also be described as cointerior?
7. What is the sum of angles d and e? (d + e)?
8. What is the sum of the other pair of co-interior angles?
9. Angles d and f are described as alternate angles. Which other pair of angles could also be described as
alternate angles?
10. What can you say about the sum of alternate angles?
Part D: Conclusion
Copy and complete the following statements:




Vertically opposite angles are always
Corresponding angles are always
Adjacent angles always add up to
Co-interior angles always add up to
.
.
.
.
Part E: Is this always true?
Investigate whether the conclusions you made are always true by ruling another transversal across your parallel lines
and investigating vertically opposite, corresponding, adjacent and co-interior angles.
Part F: Glossary
Using the online dictionary www.amathsdictionaryforkids.com/dictionary.html , look up the definitions of each of
the following terms and copy these into your glossary:







Parallel
Transversal
Supplementary
Vertically opposite angles
Corresponding
Adjacent
Interior angle
Part G: Exercise 5F
Do the following questions from Exercise 5F Parallel and Perpendicular lines.
 Question 3, 6, 7 & 8
 Questions 12,13