What is the missing reason in the proof?
Given: trapezoid ABCD with diagonal BD
Prove: triangle ABD=triangle CDB
https://study.ashworthcollege.edu/access/content/group/af6e8f9f-40f5-4e73-9bd7-b87e13cc6d33/geometry_exam_6_files/mc005-4.jpg
Statements Reasons
1.AD||BC 1.Definition of parallelogram
2.

Question

What is the missing reason in the proof?
Given: trapezoid ABCD with diagonal BD
Prove: triangle ABD=triangle CDB
 https://study.ashworthcollege.edu/access/content/group/af6e8f9f-40f5-4e73-9bd7-b87e13cc6d33/geometry_exam_6_files/mc005-4.jpg
 Statements                                Reasons 
1.AD||BC                                       1.Definition of parallelogram
2.<ADB=<CBD                              2. Alternate Interior Angles Theorem
3.AB||CD                                       3. Definition of parallelogram
4.<ABD=<CDB                              4. Alternate Interior Angles Theorem
5.DB||DB                                        5. ?
6.triangle ABD=triangle CDB            6. ASA

anonymous · Answer

A. Reflexive Property of Congruence 	
  B. Alternate Interior Angles Theorem 	
  C. ASA 	
  D. Definition of parallelogram