In the figure, AB | | CD and LEIJ = LGJI. O I Complete the following statements to prove that ZIKL and ZJLD are supplementary angles. It is given that LEIJ = LGJI. Also, LEIJ = LIKL and LGJI = ZJLK, as they are corresponding angles for parallel lines cut by a transversal. By the definition of congruent angles, m LEIJ = mLGJI, mLEIJ = mZIKL, and m /GJI = mZJLK. So, mLIKL = mZJLK by the Angle JLK and ZJLD are supplementary angles by the v , so m LJLK + mZJLD = 180 By the Substitution Property of Equality , mZIKL + mZJLD = 180 Therefore, LIKL and ZJLD are supplementary angles by definition