Gustavo noticed that when a pair of parallel lines was cut by a transversal, a certain pair of adjacent angles formed a straight line. What can he conclude from this observation? that each of the angles must measure 90°

that the angles must be complementary

that the angles must be supplementary

that each of the angles must measure 180°

Given: lines a and b are parallel and line c is a transversal. prove: 2 is supplementary to 8 what is the missing reason in the proof? statement reason 1. a || b, is a transv 1. given 2. ∠6 ≅ ∠2 2. ? 3. m∠6 = m∠2 3. def. of congruent 4. ∠6 is supp. to ∠8 4. def. of linear pair 5. ∠2 is supp. to ∠8 5. congruent supplements theorem corresponding angles theorem alternate interior angles theorem vertical angles theorem alternate exterior angles theorem