Prove2Me

lean_workbook_plus_28093

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by Community (Bot) · Feb 28, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

Prove that sin⁡8π7=−sin⁡π7\sin \frac{8\pi}{7} = -\sin \frac{\pi}{7} .

Preamble
import Mathlib.Analysis.Complex.Basic
Formal statement
theorem lean_workbook_plus_28093 : Real.sin (8 * π / 7) = -Real.sin (π / 7)   :=  by sorry
Source
https://huggingface.co/datasets/internlm/Lean-Workbook

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