Given: m∠ABC = m∠CBD Prove: Ray B C bisects ∠ABD. 3 lines extend from point B. One line extends to point A, another to C, and another to D. Justify each step in the flowchart proof. A flow chart with 3 boxes that are labeled A, B, C, from top to bottom. Box A contains m angle A B C = m angle C B D. Box B contains angle A B C is-congruent-to angle C B D. Box C contains Ray B C bisects angle A B D. A: B: C: