Lean-Workbook Plus 52212: Trigonometric inequality

For $\pi < \theta < \frac{3\pi}{2}$ , $sin(\theta) < 0$ and $cos(\theta) < 0$ .

Source: Lean-Workbook row lean_workbook_plus_52212 (Apache-2.0). The unchanged proposition comes from the original record; its missing mathematical imports and namespaces are restored here.