Explain the connection between ∠2 and ∠B.

Answer:

The sum of the interior angles of a triangle is 180°, so m∠B + 50° + 65° = 180°, which means m∠B = 65°. Similarly, the three angles on the horizontal line form a straight angle, so m∠2 + 50° + 65° = 180°, which means m∠2 = 65°. Therefore, ∠2 and ∠B are congruent because they have the same measure.