To fill in the blank, the appropriate term would be "congruent." The complete sentence would read:
"Apply angle relationships to identify congruent triangles created by transversals and parallel lines."
When two parallel lines are cut by a transversal, several pairs of angles are formed, including alternate interior angles, corresponding angles, and same-side interior angles. These relationships can be used to prove that certain triangles are congruent based on criteria such as Angle-Angle-Angle (AAA), Angle-Side-Angle (ASA), Side-Angle-Side (SAS), or Side-Side-Side (SSS).