A
B
X
Given: BA BC, and BX bisects
4
Proof: BA BC is given. Z1 Z2 by the definition of an angle
bisector. BX BX by the reflexive property of congruence.
Therefore, AABX
ACBX by the
postulate. Finally,
ZA ZC because corresponding parts of congruent triangles are
congruent.
Which of the following correctly completes the proof of the isosceles triangle theorem?