We need to remember the relationships between the angles that a transversal makes when it crosses a pair of parallel lines:

We also need to know their names, so we need to know what are;

• vertically opposite angles;
• corresponding angles;
• alternate angles; and
• interior angles.

Using this information, let’s complete exercise 6 on page 7 of the core textbook (and if we have time, questions 4 to 9 of exercise 3 on page 141 of the extended textbook):

The answers are below: