Wzór na długość łuku okręgu :
[tex]l=\dfrac{\alpha\cdot2\pi r}{360^o}[/tex]
a]
[tex]r=8 \ cm, \ \alpha=90^o\\\\l=\dfrac{90^o\cdot2\pi\cdot8}{360^o}=\dfrac{2\pi\cdot8}{4}=\dfrac{16\pi}{4}=\boxed{4\pi \ [ \ cm \ ]}[/tex]
b]
[tex]r=24 \ dm, \ \alpha=45^o\\\\l=\dfrac{45^o\cdot2\pi\cdot24}{360^o}=\dfrac{2\pi\cdot24}{8}=\dfrac{48\pi}{8}=\boxed{6\pi \ [ \ dm \ ]}[/tex]
