The proof that ΔABC ≅ ΔCDA is shown. Given: ∥ Line segment A B is parallel to line segment C D and Line segment B C is parallel to line segment D A ∥ Prove: ΔABC ≅ ΔCDA Parallelogram A B C D is shown. A line is drawn from point A to point C to form 2 triangles. What is the missing reason in the proof? Statements Reasons 1. AB ∥ CD; BC ∥ DA 1. Given 2. Quadrilateral ABCD is a ▱ 2. Definition of parallelogram 3. AB ≅ CD; BC ≅ DA 3. Opposite sides of a parallelogram are ≅ 4. AC ≅ AC 4. Reflexive property 5. ΔABC ≅ ΔCDA 5. ? perpendicular bisector theorem Pythagorean theorem HL theorem SSS congruence theorem