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

Answer 1

I' m thinking it is neither of them

Answer 2

its 2 = 4 by transitive property

Answer 3

So Joby's proof is correct

Answer 4

Joby's proof can't be correct, he uses the fact that "vertical angles are congruent" to prove that "vertical angles are congruent", that can never be a valid proof.
Diana's proof is the right one, if 1+2=180°, 2 must be equal to 180°-1
And if 1+4 = 180°, 4 must be equal to 180°-1
If 2 = 180°-1 and 4 = 180°-1, 2 = 4

Answer 5

Diana didn't complete the proof.

Answer 6

Its not diana

Answer 7

Well, it sure isn't Joby.
Diana didn't complete the proof, but the last step is kind of obvious.

Answer 8

so its neither then