Chapter 3: Angle and Line Relationships
-
A transversal is a line that intersects two or more lines. In the diagram, the purple line is the transversal.
-
Corresponding angles are angles in corresponding positions. In the diagram, ∠1 and ∠3 are congruent if the lines are parallel.
-
Alternate interior angles are on opposite sides within the parallel lines. If the lines are parallel, then the alternate interior angles are congruent. ∠1 and ∠5 are congruent. ∠4 and ∠2 are congruent.
-
Alternate exterior angles are on opposite sides outside the parallel lines. If the lines are parallel, then the alternate exterior angles are congruent. ∠8 and ∠6 are congruent. ∠7 and ∠3 are congruent. Forms a z-shape.
-
Consecutive interior angles lie on the same side of the transversal. If the lines are parallel, ∠1 and ∠2 are supplementary. Additionally, ∠3 and ∠8 are supplementary.
