In the diagram AB and CD intersect at E and AC || DB. If m

See the proof.

Step-by-step explanation:

Statement                                                               Reason

1.∠1 and ∠2 are supplementary angles     ---           Given  

2. m∠1 + m∠2 = 180°     ---                  Linear pair, they are supplementary                                

3. m∠1  and m∠3 are supplementary angles --  m∠1 + m∠3= 180

                                                                              (Supplementary angles add upto 180 degrees)  

4.  m∠1 and m∠3                                           Exterior sides in opposite rays

5.   m∠1 + m∠2 = m∠1 + m∠3                         Transitive property  

6.    m∠2 = m∠3                                    Subtraction  property

7.   l || m   If two lines are cut by transversal the alternative interior

                               angles are the same, then the lines are paralle.

Thank you.