Year 9 Interactive Maths - Second Edition

Parallel Lines

Note:

Arrows are placed on the lines AB and CD to indicate that they are parallel.

A line that meets two or more parallel lines is called a transversal.  Line PQRS in the following diagram is a transversal.

• z and x (or u and v) are alternate angles
• x and y are corresponding angles
• u and x (or z and v) are allied or co-interior angles
• y and z are vertically opposite angles

Recall that:

• Alternate angles are always equal.
• Corresponding angles are always equal.
• Allied (or co-interior) angles are supplementary.
• Vertically opposite angles are always equal.

Example 6

Use the information given in the diagram to find:

a.  x
b.  y
c.  z
d.  u
e.  p

Solution:

Key Terms

parallel lines, transversal, alternate angles, corresponding angles, co-interior angles, vertically opposite angles, allied angles