Prove2Me

Lean-Workbook Plus 17784: Trigonometric identity

Proved
WorkbookRestored.plus_17784

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

lean-workbookrestored-importssource-checked

The function f(x)=sin⁡x/(1+x4)f(x)=\sin x/(1+x^4) is odd: f(−x)=−f(x)f(-x)=-f(x) for every real xx.

Source: Lean-Workbook row lean_workbook_plus_17784 (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_17784 (f : ℝ → ℝ) (f_def : ∀ x, f x = sin x / (1 + x ^ 4)) : ∀ x, f (-x) = -f x   :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_17784; immutable original Prove2Me node d07fb2cb-fccc-4c62-8695-7b87ffb754a4

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