Question

identify the pair of congruent angles in each diagram.

Explanation:

Step1: Recall vertical - angle property

Vertical angles are congruent. In the first diagram, ∠1 and ∠3 are vertical angles.

Step2: Recall corresponding - angle property

In the second diagram, if the lines are parallel, corresponding angles are congruent. ∠4 and ∠6 are corresponding angles.

Step3: Recall alternate - interior - angle property

In the third diagram, if the lines are parallel, alternate - interior angles are congruent. ∠7 and ∠9 are alternate - interior angles.

Answer:

Diagram 9: ∠1 and ∠3; Diagram 10: ∠4 and ∠6; Diagram 11: ∠7 and ∠9