 # Selina Solutions Class 9 Mathematics Solutions for Exercise 9(B) in Chapter 9 - Chapter 9- Triangles [Congruency in Triangles]

In parallelogram ABCD, the angles A and C are obtuse. Points X and Y are

taken on the diagonal BD such that the angles XAD and YCB are right angles.

Prove that: XA=YC.

Solution  Video transcript
"hello students my name is rabbit singh and i welcome you all to ludo learning homework one of india's best online classes now today in this video we have a question that is based on the topic of parallelogram the question says in the parallelogram abcd now this is a b c d this is x and this is y the angles a and c are obtuse point x and y are taken on the diagonal we have labeled it you can see b d is the diagonal and x is and y are the points on the diagonal such that angle x a d that means angle x a d this angle and angle y c b y c b this angle they are 90 degree and hence we have to prove x a that means this equal to y c that means this so let us consider the two triangles that we have to prove x a d and y c b first thing that we have already discussed they are 90 degree so that we have written a d is equal to b c ad is equal to bc they are equal why they are equal opposite sides of parallelogram similarly if you check angle xda x d a this angle will be equal to y bc this angle why they are equal alternate angles because opposite sides are parallel so they will become alternate interior angles now based on this side angle side angle criterion we have angle x triangle xd congruent to triangle ycp that we have to prove so based on that we have x a equal to y c that is corresponding sides or we can say cpct corresponding sides of congruent triangles so i hope you have understood the concept very clearly but still if you have any doubt do comment in the comment box and please like and subscribe our channel for lido thank you"
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