 So friends in this question Figure has been given and few angles have been shown and we have to prove that a b is parallel to e f Okay, a b is parallel to e f. So how do we think and how we approach this problem? So let's in such problems. It's always a good idea to actually start from whatever is to be proven Let's say it is to be proved that a b is parallel to e f Now think about the case when a b is actually e f parallel to e f then what will happen and see whether the Conditions match with the given conditions So if a b has to be parallel to e f then and let's say cd is a third line So if we somehow prove that both a b is parallel to cd as well as e f is parallel to cd then from this logic, we can say a b is parallel to e f and And a b is parallel to cd. So for that we need to show that either alternate angles are equal or Vertically opposite or sorry corresponding angles must be equal and things like that So let's work on this thing and try to solve this problem. So consider a b and cd now So if you see angle a b c is equal to 66 degrees Okay, and Angle b cd looks like it is it is also said, you know 66 y 36 plus 30 which is equal to 66 degree and both these are actually nothing but alternate interior angles, isn't it? You look closely. So hence from this we can we can say that a b is parallel to cd since alternate interior angles are Right now one part of the question is done So now we have to prove that e f is somehow parallel to cd now if you look closely again So this angle 30 degree and this 150 degree They are complementary to each other and they happen to be adjacent angles as well So now you can say angle f e c plus angle d c e is equal to 30 degrees plus 150 degrees Which is equal to 180 degrees, isn't it? That means again by this logic E f is parallel to cd and why is that? Supplementary adjacent angles right no supplementary Adjacent angles Angles so hence Right, so from let's say this is called one and let's say two so you can now where you will say from One and two What is it a b is parallel to? CD and e f is parallel to CD so hence a b is parallel to E f guys and hence proved Okay, hence proved. I Hope you understood how to solve such problems