Lean-Workbook Plus 52577: Trigonometric identity

Proved

WorkbookRestored.plus_52577

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

lean-workbookrestored-importssource-checked

For every integer $n$ , $\cos((2n+1)\pi/2)=0$ .

Source: Lean-Workbook row lean_workbook_plus_52577 (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_52577 : ∀ n : ℤ, cos ((2 * n + 1) * π / 2) = 0   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_52577; immutable original Prove2Me node 97ba2696-1b2b-4cdd-a2b9-4a71d9f3b864

View graph