Question 237403
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Your first step is in error.  Where did you get the information that anything bisected anything else?  Just because in the picture AD <b><i>looks</i></b> like a bisector of BC, and the fact that AD will ultimately turn out to <b><i>be</i></b> a bisector of BC, unless you are given the fact that it is a bisector or can prove from the information that you were given that it is a bisector, you cannot assume that it is.


"Objection!  Assumes facts not in evidence!"


"Sustained."


Your second step: Again with the bisector thing.  No, BAD congruent to CAD because it is given that BAD congruent to CAD.


Your third step is properly constructed and justified.


Your fourth step is the crux of your problem.  Instead of SAS, you should be using ASA.


Just follow the bouncing ball:


1.  BAD congruent to CAD -- Given


2.  AD congruent to AD -- Reflexive property of equality


3.  BDA is a right angle -- Definition of perpendicular


4.  CDA is a right angle -- Definition of perpendicular


5.  BDA congruent to CDA -- Transitive property of equality


6.  Triangle BDA congruent to Triangle CDA -- ASA


7.  AB congruent to AC -- Corresponding sides of congruent triangles


8.  Triangle ABC is isosceles -- Definition of isosceles 


QED


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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