Answer:
alternate interior angles theorem
Explanation:
The alternate interior angles theorem states that when two parallel lines are cut by a transversal, the resulting angles produced are a pair of congruent alternate interior angles.
Given the image attached below, both line k and line l are parallel to each other and also, line t is the transversal, therefore the resulting congruent alternate interior angles produced are:
∠ 4 ≅ ∠6, ∠1 ≅ ∠7