Here’s how to complete the two-column proof that parallelogram ABCD with congruent diagonals \( \overline{DB} \) and \( \overline{AC} \) is a rectangle:
| Statement | Reason | |---------------------------------------------------------------|-------------------------------------------------| | 1. \( ABCD \) is a parallelogram. | Given | | 2. \( \overline{DB} \cong \overline{AC} \) | Given | | 3. \( \overline{DA} \cong \overline{CB} \) | Opposite sides of a parallelogram are congruent. | | 4. \( \overline{AB} \cong \overline{BA} \) | Reflexive Property of Congruence | | 5. \( \triangle BAD \cong \triangle ABC \) | SSS Congruence Theorem | | 6. \( \angle BAD \cong \angle ABC \) | CPCTC theorem of congruence | | 7. \( m \angle BAD = m \angle ABC \) | Definition of congruence | | 8. \( m \angle BAD + m \angle ABC = 180° \) | Consecutive angles of a parallelogram are supplementary | | 9. \( m \angle BAD + m \angle BAD = 180° \) | Substitution property of equality | | 10. \( 2m \angle BAD = 180° \) | Combine like terms | | 11. \( m \angle BAD = 90° \) | Division Property of Equality | | 12. \( m \angle ABC = 90° \) | Transitive Property of Equality | | 13. \( m \angle ADC = m \angle DAB = 90° \) | Opposite angles of a parallelogram are congruent | | 14. \( \angle BAD, \angle DCB, \angle ABC, \) and \( \angle ADC \) are right angles | Definition of a right angle | | 15. \( ABCD \) is a rectangle. | Definition of a rectangle |
You would place the responses in the correct areas as indicated above.