Odpowiedź :
[tex]P_w=\frac{\alpha}{360^o}\cdot\pi r^2\\\\\frac{\alpha}{360^o}\cdot\pi \cdot30^2=180\pi\ \ \ |:\pi\\\\\frac{\alpha}{360^o}\cdot900=180\ \ \ |:900\\\\\frac{\alpha}{360^o}=\frac{1}{5}\\\\5\alpha=360^o\ \ \ |:5\\\\\alpha=72^o[/tex]
[tex]P_w=\frac{\alpha}{360^o}\cdot\pi r^2\\\\\frac{\alpha}{360^o}\cdot\pi \cdot30^2=180\pi\ \ \ |:\pi\\\\\frac{\alpha}{360^o}\cdot900=180\ \ \ |:900\\\\\frac{\alpha}{360^o}=\frac{1}{5}\\\\5\alpha=360^o\ \ \ |:5\\\\\alpha=72^o[/tex]