Give a formal proof for the theorem. If two lines are cut by a transversal so that a pair of alternate exterior angles are congruent, then these lines are parallel. m Ci Given: lines { and m and transversal t; --Select-- v Prove: Select--- v Statements Reasons 1. lines { and m and transversal t; ---Select--- v 1. ---Select--- 2. --Select-- 2. --Select--- 3. ---Select-- 3 Select--- 4. --Select-- v 4 Select