3. provide reasons for the proof. given: 2  4 and 2 and 3 are supplementary prove: 1  3 statement reason 1. 2  4 1. given 2. m2 = m4 2. angle congruence postulate 3. 2 and 3 are supplementary 3. given 4. m2 + m3 = 180 4. definition of supplementary angles 5. 1 and 4 are supplementary 5. 6. m1 + m4 = 180 6. definition of supplementary angles 7. m1 + m4 = m2 + m3 7. 8. m1 + m4 = m4 + m3 8. 9. m1 = m3 9. 10. 1  3 10.