Statement Reason
1. altitude AD bisects ∠BAC 1. Given
2. DB is congruent to DC 2. definition of bisect
3. m∠BDA = 90° 3. definition of altitude
4. m∠CDA = 90° 4. definition of altitude
5. m∠BDA = m∠CDA 5. transitive property
6. AD is congruent to AD 6. reflexive property
7. tri BDA is congruent to tri CDA 7. SAS
8. AB is congruent to AC 8. CPCTC
9. tri ABC is isosceles 9. definition of isosceles