Theorem 3eqtr3a 2253

Description: A chained equality inference, useful for converting from definitions. (Contributed by Mario Carneiro, 6-Nov-2015.)

Hypotheses

Ref	Expression
3eqtr3a.1	|- A = B
3eqtr3a.2	|- ( ph -> A = C )
3eqtr3a.3	|- ( ph -> B = D )

Assertion

Ref	Expression
3eqtr3a	|- ( ph -> C = D )

Proof of Theorem 3eqtr3a

Step	Hyp	Ref	Expression
1		3eqtr3a.2	. 2 |- ( ph -> A = C )
2		3eqtr3a.1	. . 3 |- A = B
3		3eqtr3a.3	. . 3 |- ( ph -> B = D )
4	2, 3	eqtrid 2241	. 2 |- ( ph -> A = D )
5	1, 4	eqtr3d 2231	1 |- ( ph -> C = D )

Syntax hints:   -> wi 4   = wceq 1364

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1461  ax-gen 1463  ax-4 1524  ax-17 1540  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-cleq 2189

This theorem is referenced by:  uneqin  3415  coi2  5187  foima  5488  f1imacnv  5524  fvsnun2  5763  fnsnsplitdc  6572  phplem4  6925  phplem4on  6937  halfnqq  7494  resqrexlemcalc1  11196  absefib  11953  efieq1re  11954  restopnb  14501  cnmpt2t  14613  reeflog  15183  rpcxpsqrt  15242