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Theorem unundi 3758
Description: Union distributes over itself. (Contributed by NM, 17-Aug-2004.)
Assertion
Ref Expression
unundi (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))

Proof of Theorem unundi
StepHypRef Expression
1 unidm 3740 . . 3 (𝐴𝐴) = 𝐴
21uneq1i 3747 . 2 ((𝐴𝐴) ∪ (𝐵𝐶)) = (𝐴 ∪ (𝐵𝐶))
3 un4 3757 . 2 ((𝐴𝐴) ∪ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))
42, 3eqtr3i 2645 1 (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))
Colors of variables: wff setvar class
Syntax hints:   = wceq 1480  cun 3558
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-v 3192  df-un 3565
This theorem is referenced by:  dfif5  4080
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