Question

Diana and Joby wrote the following proofs to prove that vertical angles are congruent. Who is correct?



Diana's Proof



Statement

Justification

∠ 1 + ∠ 2 = 180° Definition of Supplementary Angles
∠ 1 + ∠ 4 = 180° Definition of Supplementary Angles
∠ 1 + ∠ 2 = ∠ 1 + ∠ 4 Transitive Property of Equality


Joby's Proof



Statement

Justification

∠ 2 = ∠ 4 Vertical angles are congruent.
∠ 1 = ∠ 3 Vertical angles are congruent.
Vertical Angles are congruent. Vertical Angle Theorem