Lean-Workbook Plus 8751: Trigonometric identity

Proved

WorkbookRestored.plus_8751

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

lean-workbookrestored-importssource-checked

For every real angle $\theta$ , $\sin^2\theta+\cos^2\theta=1$ .

Source: Lean-Workbook row lean_workbook_plus_8751 (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_8751 (θ : ℝ) : (sin θ)^2 + (cos θ)^2 = 1   :=  by sorry

Source

https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_8751; immutable original Prove2Me node aa76da2a-9561-473c-8ad7-95bef4326a41

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