Given: ABCD is a parellelogram.
Prove: AB=CD and BC=DA

Answer:
Step-by-step explanation:
We have given a parallelogram ABCD.
For a parallelogram,
Opposite pair of sides are parallel to each other.
i.e AD is parallel to BC and AB is parallel to CD.
From the attached figure,
∡1 = ∡4 and ∡2 = ∡3 {If two parallel lines cut by a transversal line then alternate interior angles are congruent }
Next, AC ≅ AC {Reflexive identity}
hence, ΔABC ≅ ΔCDA , By Angle-Side-Angle(ASA) congruent property of triangle.
Therefore, AB = CD and AD = BC {Proved}
Parallelograms have a pair of parallel sides and angles.
The statements of proof and the reasons are:
From the question, we have:
ABCD is a parallelogram.
So, the reason for the above statement would be "Given"
From the figure, we have:
AD is parallel to BC and AB is parallel to CD.
This means that:
The angles at opposite vertices are congruent.
So, we have:
[tex]\mathbf{\angle A \cong\ \angle C \ and\ \angle B \cong \angle D}[/tex]
The reason for the above statement would be "Definition of alternate interior angles"
Also, we can see that:
Lines AC and BD are diagonals, and they meet at a point
The reason for the above statement would be "Unique line postulate"
The above statement means that:
[tex]\mathbf{AB \cong\ CD \ and\ BC \cong DA}[/tex]
The reason for the above statement would be "Definition of parallelogram"
Hence, ABCD has been proven to be a parallelogram.
Read more about proofs of parallelograms at:
https://brainly.com/question/4626921