Question 310134
"Given:Angle BAD is congruent to Angle CAD"


"Angle BDA is congruent to Angle CDA---Right Angle Theorem"


"Line segment AD is congruent to Line segment AD---Reflexive"


triangle BAD is congruent to triangle CAD---ASA


side BA is congruent to side CA---CPCTC


triangle ABC is isoc---definition



this is the essence of the proof
you may need to "touch up" a little