lean_workbook_plus_11215

Open

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

prove that : \n $3(\cos^2x+\cos^2y+\cos^2z) \geq ( \cos x+ \cos y+ \cos z)^2$

Preamble

import Mathlib.Analysis.Complex.Basic

Formal statement

theorem lean_workbook_plus_11215 (x y z: ℝ) : 3 * (Real.cos x ^ 2 + Real.cos y ^ 2 + Real.cos z ^ 2) ≥ (Real.cos x + Real.cos y + Real.cos z) ^ 2   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook

View graph