Naloge

$p_i=\displaystyle{\frac{\pi r^2 \alpha}{360^\circ}}$

$p_i=\displaystyle{\frac{\pi r^2 \alpha}{360^\circ}}$	$/\cdot 360^\circ$
$p_i\cdot 360^\circ=\pi r^2 \alpha$	$/:\pi r^2$
$\displaystyle{\frac{p_i\cdot 360^\circ}{\pi r^2}}=\alpha$ ali
$\alpha= \displaystyle{\frac{p_i\cdot 360^\circ}{\pi r^2}}$

$\alpha= \displaystyle{\frac{p_i\cdot 360^\circ}{\pi r^2}}$

$\alpha= \displaystyle{\frac{15\pi \;{\rm dm^2}\cdot 360^\circ}{\pi (6\;{\rm dm})^2}}=150^\circ$