Theorem 3eqtr3a 2291

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 2279	. 2 |- ( ph -> A = D )
5	1, 4	eqtr3d 2269	1 |- ( ph -> C = D )

Syntax hints:   -> wi 4   = wceq 1398

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 1496  ax-gen 1498  ax-4 1559  ax-17 1575  ax-ext 2216

This theorem depends on definitions:  df-bi 117  df-cleq 2227

This theorem is referenced by:  uneqin  3476  coi2  5284  foima  5600  f1imacnv  5636  fvsnun2  5887  fnsnsplitdc  6751  phplem4  7122  phplem4on  7135  halfnqq  7741  resqrexlemcalc1  11724  absefib  12482  efieq1re  12483  restopnb  15172  cnmpt2t  15284  reeflog  15854  rpcxpsqrt  15913