Theorem biadan2 429

Description: Add a conjunction to an equivalence. (Contributed by Jeff Madsen, 20-Jun-2011.)

Hypotheses

Ref	Expression
biadan2.1	⊢ (φ → ψ)
biadan2.2	⊢ (ψ → (φ ↔ χ))

Assertion

Ref	Expression
biadan2	⊢ (φ ↔ (ψ ∧ χ))

Proof of Theorem biadan2

Step	Hyp	Ref	Expression
1		biadan2.1	. . 3 ⊢ (φ → ψ)
2	1	pm4.71ri 372	. 2 ⊢ (φ ↔ (ψ ∧ φ))
3		biadan2.2	. . 3 ⊢ (ψ → (φ ↔ χ))
4	3	pm5.32i 427	. 2 ⊢ ((ψ ∧ φ) ↔ (ψ ∧ χ))
5	2, 4	bitri 173	1 ⊢ (φ ↔ (ψ ∧ χ))

Syntax hints:   → wi 4   ∧ wa 97   ↔ wb 98

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101

This theorem depends on definitions:  df-bi 110

This theorem is referenced by:  elab4g  2685  brab2a  4336  brab2ga  4358  elovmpt2  5643  eqop2  5746  elnnnn0  8001  elixx3g  8540  elfzo2  8777