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lemma proved tactic proof

phi_lt_two

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formal statement (Lean)

  71lemma phi_lt_two : phi < 2 := by

proof body

Tactic-mode proof.

  72  unfold phi
  73  have : Real.sqrt 5 < 3 := by
  74    rw [← Real.sqrt_sq (by norm_num : (0:ℝ)≤3)]
  75    apply Real.sqrt_lt_sqrt (by norm_num) (by norm_num)
  76  linarith
  77
  78/-! ## Specific Powers -/
  79
  80/-- Lower bound for φ. -/

used by (23)

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depends on (5)

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