Given: δabc is an isosceles triangle where ab = bc. prove: m∠bac = m∠bca proof: statement reason 1. let δabc be an isosceles triangle where ab = bc. given 2. create point d on so that bisects ∠abc as shown. constructing an angle bisector 3. m∠abd = m∠dbc definition of angle bisector 4. bd = bd 5. δabd ≅ δcbd sas 6. m∠bac = m∠bca corresponding angles of congruent triangles are equal. what is the reason for statement 4 in this proof? a. transitive property of equality b. definition of midpoint c. definition of parallel lines d. reflexive property of equality