Theorem 3eqtr3a 2286

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 2274	. 2 |- ( ph -> A = D )
5	1, 4	eqtr3d 2264	1 |- ( ph -> C = D )

Syntax hints:   -> wi 4   = wceq 1395

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 1493  ax-gen 1495  ax-4 1556  ax-17 1572  ax-ext 2211

This theorem depends on definitions:  df-bi 117  df-cleq 2222

This theorem is referenced by:  uneqin  3455  coi2  5245  foima  5555  f1imacnv  5591  fvsnun2  5841  fnsnsplitdc  6659  phplem4  7024  phplem4on  7037  halfnqq  7608  resqrexlemcalc1  11541  absefib  12298  efieq1re  12299  restopnb  14871  cnmpt2t  14983  reeflog  15553  rpcxpsqrt  15612