lean_workbook_plus_80393

Proved

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

Prove, that $x^2+y^2+z^2=xy+yz+zx$ if and only if x=y=z.

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_80393 (x y z: ℝ) : x^2 + y^2 + z^2 = x * y + y * z + z * x ↔ x = y ∧ y = z ∧ z = x   :=  by sorry

Source