### Transversals

A transversal is a line that crosses two other lines. In both diagrams, the line PQ is a transversal to both the lines AB and CD.

### Corresponding angles

In each of the diagrams below, the two marked angles are called corresponding angles because they are in corresponding positions around the two vertices M and N.

### Corresponding angles and parallel lines

If the lines AB and CD are parallel, then the corresponding angles $$\angle$$DGF and $$\angle$$BHF, marked $$\alpha$$ and β, are equal.

#### Example 1

Find θ in the diagram.

#### Solution

θ = 121° (corresponding angles AB || CD)