Here is the two-column proof that parallelogram ABCD with congruent diagonals DB and AC is a rectangle. I will place the statements in order with their appropriate reasons:
| Statement | Reason | |--------------------------------------------------------|-------------------------------------------------------------| | 1. ABCD is a parallelogram. | Given | | 2. DB ≅ AC | Given | | 3. DA ≅ CB | Opposite sides of a parallelogram are congruent. | | 4. AB ≅ BA | Reflexive Property of Congruence | | 5. ΔBAD ≅ ΔABC | SSS Congruence Theorem | | 6. ∠BAD ≅ ∠ABC | Corresponding parts of congruent triangles are congruent. | | 7. m∠BAD = m∠ABC | Definition of congruence | | 8. m∠BAD + m∠ABC = 180° | Consecutive angles of a parallelogram are supplementary | | 9. m∠BAD + m∠BAD = 180° | Substituting m∠ABC for m∠BAD | | 10. 2m∠BAD = 180° | Combine like terms | | 11. m∠BAD = 90° | Division Property of Equality | | 12. m∠ABC = 90° | Transitive Property of Equality | | 13. m∠ADC = m∠DAB = 90° | Opposite angles of a parallelogram are congruent | | 14. ∠BAD, ∠DCB, ∠ABC, and ∠ADC are right angles | Definition of a right angle | | 15. ABCD is a rectangle | Definition of a rectangle |
This correctly aligns the statements and reasons in accordance with the proof structure for demonstrating that parallelogram ABCD is a rectangle due to having congruent diagonals and right angles.