Odpowiedź :
[tex]sin\frac{\alpha}{2}=\frac{r}{l}\\\\sin\frac{\alpha}{2}=\frac{1}{\sqrt2}\\\\sin\frac{\alpha}{2}=\frac{\sqrt2}{2}\\\\\frac{\alpha}{2}=45^o\ \ \ |\cdot2\\\\\alpha=90^o[/tex]
d 90 stopni
[tex]sin\frac{\alpha}{2}=\frac{r}{l}\\\\sin\frac{\alpha}{2}=\frac{1}{\sqrt2}\\\\sin\frac{\alpha}{2}=\frac{\sqrt2}{2}\\\\\frac{\alpha}{2}=45^o\ \ \ |\cdot2\\\\\alpha=90^o[/tex]
d 90 stopni