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Theorem unundi 3736
 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 3718 . . 3 (𝐴𝐴) = 𝐴
21uneq1i 3725 . 2 ((𝐴𝐴) ∪ (𝐵𝐶)) = (𝐴 ∪ (𝐵𝐶))
3 un4 3735 . 2 ((𝐴𝐴) ∪ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))
42, 3eqtr3i 2634 1 (𝐴 ∪ (𝐵𝐶)) = ((𝐴𝐵) ∪ (𝐴𝐶))
 Colors of variables: wff setvar class Syntax hints:   = wceq 1475   ∪ cun 3538 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-v 3175  df-un 3545 This theorem is referenced by:  dfif5  4052
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