**Alternate Interior Angles **are pairs of angles found on the **interior** of parallel lines but on the **opposite** side of the transversal.

In the figure below, parallel lines \(m\) and \(n\) are cut by the transversal \(t\).

The pairs of the alternate interior angles are as follows:

\(\angle{1}\) and \(\angle{3}\)

\(\angle{2}\) and \(\angle{4}\)

Since the transversal intersected **parallel lines**, the alternate interior angles are **congruent**.