lean_workbook_plus_43268

Proved

by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

$a = \\frac{1 + \\sqrt{5}}{2} = \\phi$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_43268 : 1.61803399 < Real.sqrt 5   :=  by sorry

Source