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Theorem 3eqtr2ri 2168
Description: An inference from three chained equalities. (Contributed by NM, 3-Aug-2006.) (Proof shortened by Andrew Salmon, 25-May-2011.)
Hypotheses
Ref Expression
3eqtr2i.1 𝐴 = 𝐵
3eqtr2i.2 𝐶 = 𝐵
3eqtr2i.3 𝐶 = 𝐷
Assertion
Ref Expression
3eqtr2ri 𝐷 = 𝐴

Proof of Theorem 3eqtr2ri
StepHypRef Expression
1 3eqtr2i.1 . . 3 𝐴 = 𝐵
2 3eqtr2i.2 . . 3 𝐶 = 𝐵
31, 2eqtr4i 2164 . 2 𝐴 = 𝐶
4 3eqtr2i.3 . 2 𝐶 = 𝐷
53, 4eqtr2i 2162 1 𝐷 = 𝐴
Colors of variables: wff set class
Syntax hints:   = wceq 1332
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1424  ax-gen 1426  ax-4 1488  ax-17 1507  ax-ext 2122
This theorem depends on definitions:  df-bi 116  df-cleq 2133
This theorem is referenced by:  funimacnv  5206  uniqs  6494  ef01bndlem  11497  cos2bnd  11501  sinhalfpilem  12918
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