 Hi and welcome to the session. Let's discuss the following question. It says L and M are two parallel lines intersected by another pair of parallel lines P and Q. Show that triangle ABC is congruent to triangle CDA. So let us first understand the basic approach to solve it. We will be using ASA, Congruence Criteria. This approach is the K idea. Now we are given that L is parallel to M and P is parallel to Q and we have to prove that triangle ABC is congruent to triangle CDA and by the ASA criteria we need to prove that two angles and one included side of the two triangles are equal. Let's now move on to the solution. We are given that L is parallel to M and they are intersected by AC. Therefore angle DAC is equal to angle BCA. Also angle BAC is equal to angle ACD because they are alternate angles. In triangle ABC CDA angle DAC is equal to angle BCA. As we discussed above they are alternate angles and similarly angle BAC is equal to angle ACD. Now we can see that AC is the common side of both the triangles. So AC is equal to AC as it is the common side. So we have shown that two angles and one included side of both triangles are equal. Therefore by ASA criteria triangle ABC is congruent to triangle CDA by ASA criteria. Hence proved. So this completes the question. Bye for now. Take care. Hope you enjoyed the session.