# The Corresponding Angles Theorem Explained In Plain English

## What is a Corresponding Angles Theorem?

The corresponding angles theorem is a mathematical theorem that states that if two parallel lines are cut by a transversal, then the angles that are matched up in the same position on each side of the transversal are equal. This theorem is often referred to as the “corresponding angles theorem” or the “angle-angle theorem.” It is an important theorem in the field of geometry and is used to solve many mathematical problems.

## What is a Transversal?

A transversal is a line that intersects two or more other lines. In the case of the corresponding angles theorem, the transversal is cutting through two parallel lines. The transversal is also referred to as a “third line.” The transversal must intersect the two parallel lines in order for the theorem to work.

## How Does the Corresponding Angles Theorem Work?

The corresponding angles theorem states that if two parallel lines are cut by a transversal, then the angles that are matched up in the same position on each side of the transversal are equal. This means that if two angles on one side of the transversal are equal, then the corresponding angles on the other side of the transversal are also equal. This can be seen in the illustration below.

## Why is the Corresponding Angles Theorem Useful?

The corresponding angles theorem is useful because it can be used to solve many mathematical problems. For example, it can be used to determine the angle measures of triangles when given the lengths of their sides. It can also be used to determine the lengths of unknown sides of a triangle when given the lengths of two sides and the angle measure between them. In addition, the corresponding angles theorem can be used to prove whether or not two lines are parallel.

## What is the Difference Between the Corresponding Angles Theorem and the Alternate Angles Theorem?

The corresponding angles theorem states that if two parallel lines are cut by a transversal, then the angles that are matched up in the same position on each side of the transversal are equal. The alternate angles theorem states that if two parallel lines are cut by a transversal, then the angles that are opposite each other (i.e., on different sides of the transversal) are equal. These two theorems are similar but not the same.

## What Other Theorems Are Related to the Corresponding Angles Theorem?

The corresponding angles theorem is related to several other theorems, including the perpendicular bisector theorem, the alternate interior angles theorem, the alternate exterior angles theorem, and the parallel line theorem. All of these theorems involve angles and can be used to solve mathematical problems.

## Conclusion

The corresponding angles theorem is an important theorem in the field of geometry. It states that if two parallel lines are cut by a transversal, then the angles that are matched up in the same position on each side of the transversal are equal. This theorem is useful for solving many mathematical problems, and it is related to several other theorems, including the perpendicular bisector theorem, the alternate interior angles theorem, the alternate exterior angles theorem, and the parallel line theorem.