Answer
1. $\angle ABC$ is a right angle
2. $m\angle ABC=90^{\circ}$
3. $m\angle 1 + m\angle 2=m\angle ABC$
4. $m\angle 1 + m\angle 2=90^{\circ}$
5. Ray BD bisects $\angle ABC$
6. $m\angle 1 = m\angle 2$
7. $m\angle 1+m\angle 1=90^{\circ}$
8. $m\angle 1=45^{\circ}$
Work Step by Step
1. Given
2. Definition of a right angle
3. Angle addition postulate
4. Substitution property of equality
5. Given
6. Definition of Angle Bisector
7. Substitution property of equality
8. Division property of equality
