Answer:
Vertically opposite angles.
Explanation:
A line is a one-dimensional figure having no thickness and extends infinitely in both the directions.
Intersecting lines are the lines which intersect at one point.
Parallel lines which do not intersect at any point.
An angle is formed by two rays meeting at a common end point.
Vertically opposite angles are the angles formed opposite to one another at the intersection of two lines.
Vertically opposite angles are always equal.