r = 10 cm
\alpha = 12^{\circ}
Z teorii
\frac{\alpha}{360^{\circ}}=\frac{P_w}{\pi r^2}
\frac{12^{\circ}}{360^{\circ}}=\frac{P_w}{\pi \cdot 10^2}
\frac{1}{30}=\frac{P_w}{100\pi}
30P_w=100\pi \ |:30
P_w=\frac{100\pi}{30}=\frac{10\pi}{3}\approx 10,5 \ cm^2 <-- odpowiedź