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

Use the information in the given figure to prove:

(i) AB=FE

(ii) BD=CF Solution Video transcript
"hello students my name is rabbit singh and i welcome you all to lido 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 congruent triangles the question says use the information in the given figure to prove a b is equal to fe now where is a b this is a b is equal to fe and b d is equal to c f b d is equal to c f so we have in triangle abc you can see this is triangle abc and triangle efd e f d a b is parallel to e f it is already given so angle abc that means angle a b c this angle will be equal to angle e f d e f d why they are equal they are alternate angles so this is the first condition angles ac is equal to e d that is already given you can check ac in the figure is equal to 80 that is given so that is side so third angle acb this this angle is equal to angle this that is also given that is third part now based on this if you check side angle side angle or aas congruence criterion triangle abc is congruent to triangle efd so based on this we have a b is equal to fe cpct corresponding part of congruent triangle and bc is equal to df vc is equal to df that's also by cpct now where is bc this is bc that is equal to df this part now but we have to prove bd is equal to cf this and this so what we will do we will add bd plus we will break bc in two part that will be bd plus dc and cf also cf plus dc now after that we will cancel dc from both sides and with the expression that we will be getting is vd is equal to cf that we have to prove 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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