11.5 Alternate angles

Introduction

Starting with a list of all angles in a parallel line:

An example of corresponding angles (already discussed) are b and f, meaning $b=f$ .

An example of vertically opposite angles (already discussed) are b and c, meaning $b=c$ .

Since $b=f$ and $b=c$ , therefore, $c=f$ . These angles are called alternate angles, since they are on alternate sides of the transversal.