Answer:
The missing reason for the 3rd step in the proof below is;
C. Vertical angles are congruent
Step-by-step explanation:
In the two column proof, we have;
Statement [tex]{}[/tex] Reason
1. AB ║ CD [tex]{}[/tex] 1. Given
2. ∠3 ≅ ∠7 [tex]{}[/tex] 2. Corresponding angles theorem
3. ∠7 ≅ ∠6 [tex]{}[/tex] 3. Vertical angles are congruent
4. m∠3 = m∠7 [tex]{}[/tex] 4. Definition of congruence
m∠7 = m∠6
5. m∠3 = m∠6 [tex]{}[/tex] 5. Substitution
6. m∠3 ≅ m∠6 [tex]{}[/tex] 6. Definition of congruence
Vertical angles are the angles formed on the opposite sides of two straight lines when they cross each other
Other vertical angles in the diagram are;
1) ∠5 and ∠8
2) ∠1 and ∠4
3) ∠2 and ∠3
