flowchart proof
1) Lines m and l are parallel ------> given
2) ∠1 ≅ ∠2 -----> by alternate interior angles
3) ∠3 ≅ ∠2 -----> by vertical angles
4) ∠1 ≅ ∠3 ----> by the transitive property
4.3m questions
5.6m answers