Exercise 2 Page 507

Let's classify the pair of angles wee see in the diagram.
&∠ 1 and ∠ 3 are corresponding angles. &∠ 2 and ∠ 3 are consecutive interior angles. &∠ 2 and ∠ 4 are alternate interior angles. &∠ 1 and ∠ 5 are alternate exterior angles. Because, the lines cut by the transversal are parallel, we can relate these pairs of angles by the ... Corresponding Angles Theorem, Consecutive Interior Angles Theorem, Alternate Interior Angles Theorem, Alternate Exterior Angles Theorem

One of the theorems does not describe congruent angles, namely the Consecutive Interior Angles Theorem. This theorem describes supplementary angles. Therefore, ∠ 2 and ∠ 3 do not belong with the other three pairs.