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 1397

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 1495  ax-gen 1497  ax-4 1558  ax-17 1574  ax-ext 2213

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

This theorem is referenced by:  uneqin  3458  coi2  5253  foima  5564  f1imacnv  5600  fvsnun2  5852  fnsnsplitdc  6673  phplem4  7041  phplem4on  7054  halfnqq  7630  resqrexlemcalc1  11592  absefib  12350  efieq1re  12351  restopnb  14924  cnmpt2t  15036  reeflog  15606  rpcxpsqrt  15665