It is given that m∥n , m∠1=50∘ , m∠2=48∘ , and line s bisects ∠abc . by the , m∠def=98∘ . because angles formed by two parallel lines and a transversal are congruent, ∠def≅∠abc , so m∠abc=98∘ . by the , angles 4 and 5 are congruent, and m∠4 is half m∠abc . so the measure of m∠4=49∘ . because vertical angles are congruent, ∠3≅∠4 . finally, m∠3=m∠4 by the angle congruence postulate, so m∠3=49∘ by the .