Theorem 3eqtr3a 2288

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 2276	. 2 |- ( ph -> A = D )
5	1, 4	eqtr3d 2266	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 2213

This theorem depends on definitions:  df-bi 117  df-cleq 2224

This theorem is referenced by:  uneqin  3460  coi2  5260  foima  5573  f1imacnv  5609  fvsnun2  5860  fnsnsplitdc  6716  phplem4  7084  phplem4on  7097  halfnqq  7690  resqrexlemcalc1  11654  absefib  12412  efieq1re  12413  restopnb  14992  cnmpt2t  15104  reeflog  15674  rpcxpsqrt  15733