Statements Reasons
1. Write all the given as you did 1. Given
2. <DBA and <DBC are right angles 2. Def of perpendicular lines
3. m<DBA = 90 3. Def of right angle
m<DBC = 90
4. m<DBA = m<DBC 4. Substitution
5. m<DBA = m<1 + m<3 5. Angle addition postulate
m<DBC = m<2 + m<4
6. m<1 + m<3 = m<2 + m<4 6. Substitution
7. m<3 = m<4 7. Subtraction prop of equality