Proof in geometry: you are given that line ab is congruent to line cd; line ab is parallel to line cd. you are trying to prove that line ad is parallel to line bc.
statements are as follow:
1. line ab is congruent to line cd; line ab is parallel to line cd.
2. line ac is congruent to line ac.
3. angle 1 is congruent to angle 3.
4. triangle abc is congruent to triangle cda.
5.
6. therefore, line ad is parallel to line bc.

reasons are as follow:
1. given.
2.
3.
4.
5. cpctc.
6.