lean_workbook_plus_10773

Proved

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

$\frac{\sqrt{2-\sqrt{2}}}{2} =\frac{\sqrt{2}}{2}\cdot \sqrt{1-\frac{\sqrt{2}}{2}}=\frac{\sqrt{2}}{2}\cdot \sqrt{1-\cos\frac{\pi}{4}}$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_10773 : (Real.sqrt (2 - Real.sqrt 2)) / 2 = (Real.sqrt 2 / 2) * Real.sqrt (1 - Real.sqrt 2 / 2)   :=  by sorry

Source