Parallel Lines 70F141

1. The problem asks to complete the statement: "If two lines form ___ interior angles on the same side of the transversal, then the lines are parallel." 2. This is a geometry problem involving parallel lines and a transversal. The key concept is the "consecutive interior angles" or "same-side interior angles." 3. The theorem states: If two lines are cut by a transversal and the consecutive interior angles are supplementary (sum to 180 degrees), then the lines are parallel. 4. The missing phrase is "supplementary" because the interior angles on the same side of the transversal must add up to 180 degrees for the lines to be parallel. 5. Therefore, the completed statement is: "If two lines form supplementary interior angles on the same side of the transversal, then the lines are parallel."