Prove2Me

Lean-Workbook Plus 52484: Trigonometric inequality

Proved
WorkbookRestored.plus_52484

by wamlart · Sep 12, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

lean-workbookrestored-importssource-checked

For −π/2≤x≤π/2-\pi/2\le x\le\pi/2, sin⁡2x+cos⁡x−5/4≤0\sin^2x+\cos x-5/4\le0.

Source: Lean-Workbook row lean_workbook_plus_52484 (Apache-2.0). The unchanged proposition comes from the original record; its missing mathematical imports and namespaces are restored here.

Preamble
import Mathlib.Analysis.SpecialFunctions.Trigonometric.Basic
open Real
Formal statement
theorem WorkbookRestored.plus_52484 :
  ∀ x ∈ Set.Icc (-Real.pi / 2) (Real.pi / 2), (Real.sin x)^2 + Real.cos x - 5 / 4 ≤ 0   :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_52484; immutable original Prove2Me node 8e639972-9d15-4e03-9494-d1a1b879e14d

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