Lean-Workbook Plus 34171: Trigonometric inequality

Proved

WorkbookRestored.plus_34171

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

lean-workbookrestored-importssource-checked

For every real $C$ , $\sin C(1-\sin C)\le1/4$ .

Source: Lean-Workbook row lean_workbook_plus_34171 (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_34171 : ∀ C : ℝ, sin C * (1 - sin C) ≤ 1 / 4   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_34171; immutable original Prove2Me node 7f152dbb-4b80-4f53-a649-4bdbe9861869

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