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Lean-Workbook Plus 12215: Trigonometric identity

Proved
WorkbookRestored.plus_12215

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

lean-workbookrestored-importssource-checked

The special-angle value is sin⁡(π/2)=1\sin(\pi/2)=1.

Source: Lean-Workbook row lean_workbook_plus_12215 (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_12215 : sin (π / 2) = 1   :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook/blob/main/lean_workbook.json, row lean_workbook_plus_12215; immutable original Prove2Me node 7138fec6-6e46-40bb-9b77-c863f23539b8

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