Write a two-column proof.
Given: Quadrilateral GKJH is a parallelogram
Prove: △GLH ≅ △JLK

Answer:
See explanation
Step-by-step explanation:
Statement Reason
1. GKJH is a parallelogram - Given
2. GH║KJ - Definition of the parallelogram
3. ∠HGL and ∠KJL are alternate interior angles - Definition of alternate interior angles
4. ∠HGL≅∠KJL - Alternate interior angles theorem
5. GH≅KJ - Property of parallelogram
6. ∠GLH and ∠JLK are vertical angles - Definition of vertical angles
7. ∠GLH≅∠JLK - Vertical angles thoerem
8. ΔGLH≅ΔJLK - AAS postulate