Answer:
Angles opposite one another that share a vertex are called vertical angles.
When one of these angles undergo a rigid transformation so that it fits exactly over the other, we know that the two angles are congruent
When two parallel lines are crossed by another line called the transversal the angles created inside the parallel lines but on opposite sides of the crossing lines are called alternate interior angles. Angles of this type have the same measurement as one another. Two figures are similar if one can fit exactly over the other after rigid transformations and dilations
Explanation:
Vertically opposite angles are always equal (congruent)
The transversal line is the line that crosses two or more parallel lines
Alternate interior angles formed by two parallel lines crossed by a common transversal, are congruent
Two plane geometric figures are similar if they their corresponding interior angles are congruent