Answer:
acute angle and obtuse angle
Explanation:
Parallel lines are lines that do not meet each other. When two parallel lines cut by a transversal(a line which transverse or intersect any system of other lines transversely), then we have four acute and obtuse angles.
All the acute angles and the obtuse angles are congruent angles ( i.e. coinciding exactly when being superimposed) and all the acute angles and obtuse angles are supplementary angles to each other. The congruent angles when the two parallel lines get cut by a transversal are known as alternate interior angles.