Metamath Proof Explorer


Theorem opeq12

Description: Equality theorem for ordered pairs. (Contributed by NM, 28-May-1995)

Ref Expression
Assertion opeq12 ⊢ A = C ∧ B = D → A B = C D

Proof

Step Hyp Ref Expression
1 opeq1 ⊢ A = C → A B = C B
2 opeq2 ⊢ B = D → C B = C D
3 1 2 sylan9eq ⊢ A = C ∧ B = D → A B = C D