Let's fill out the responses step by step based on the given information about quadrilateral LAND and the properties of the angles:
Question 1
Given:
- \( \angle ALN \cong \angle DNL \)
- \( \angle ANL \cong \angle DLN \)
To prove that angles imply parallel sides:
- If \( \angle ALN \cong \angle DNL \), then \( LA \parallel ND \).
- If \( \angle ANL \cong \angle DLN \), then \( LN \parallel AD \).
Question 2
The theorem used to identify that the opposite sides are parallel is:
- If the alternate interior angles are congruent, then the lines are parallel.
Question 3
The way used to confirm that the quadrilateral was a parallelogram:
- If one pair of sides is both congruent and parallel, then the quadrilateral is a parallelogram.
Putting it all together, here are the final answers:
- If \( \angle ALN \cong \angle DNL \), then \( LA \parallel ND \).
- If \( \angle ANL \cong \angle DLN \), then \( LN \parallel AD \).
- If the alternate interior angles are congruent, then the lines are parallel.
- If one pair of sides is both congruent and parallel, then the quadrilateral is a parallelogram.