Yes.

According to Euclid’s 5^{th} postulate, when n line falls on l and m and if ∠1 + ∠2 < 180**°**, then ∠3 + ∠4 > 180**°**producing line l and m further will meet in the side of ∠1 and ∠2 which is less than 180**°**.

The lines l and m neither meet at the side of ∠1 and ∠2 nor at the side of ∠3 and ∠4. This means that the lines l and m will never intersect each other. Therefore, it can be said that the lines are parallel.