Given:In quadrilateral WXYZ , and bisect each other at point A. Prove: Quadrilateral WXYZ is a parallelogram. Statement Reason 1. and bisect each other. given 2. WA = YA XA = ZA definition of bisection 3. m∠YAZ = m∠XAW Vertical Angles Theorem 4. SAS criterion for congruence 5. ∠ YWX ≅ ∠WYZ Corresponding angles of congruent triangles are congruent. 6. || converse of Alternate Interior Angles Theorem 7. m∠XAY = m∠ZAW Vertical Angles Theorem 8. ∆XAY ≅ ∆ZAW SAS criterion for congruence 9. ∠XZW ≅ ∠ZXY Corresponding angles of congruent triangles are congruent. 10. || converse of Alternate Interior Angles Theorem 11. Quadrilateral WXYZ is a parallelogram. definition of parallelogram What is the missing statement in this proof?What is the missing statement in this proof?