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

Question 12 Exercise 9(B)

In a triangle, ABC, AB=BC, AD is perpendicular to side BC and CE is

perpendicular to side AB. Prove that:

Solution

Video transcript
"hello students my name is rabbit singh and i welcome you all to leader learning homework one of india's best online classes now today in this video we have a question that is based on the topic congruent triangles the question says in a triangle abc ab is equal to bc now you can check this is a b and it is equal to bc that is given and a d is perpendicular to side bc now you can see we have drawn a d and that is perpendicular that means 90 degree and ce is perpendicular to a b this is c e and it is perpendicular to side a b what we have to prove prove that a d that is this side is equal to c basically we have to prove the perpendicular to be equal now if you check we will be using the congruent triangle conditions in triangle abd whereas abd a b d and triangle c b e so let us mark that with different colors a b d this triangle and second one is c b e c b e this triangle a b is equal to bc that is already given so that is side now angle adb angle a d b this angle and angle c e b angle c e b 90 degree that is because altitude and second last part you can check angle b is common this is angle b this is common to both of them so this is common now this becomes angle and the last one becomes angle now we have side angle side congruent triangle so angle triangle abd becomes congruent to triangle cbe we have proved that now based on this we will prove a d is equal to c e y according to cpct corresponding parts of congruent triangle 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 i can subscribe our channel for lido thank you "
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