Ответ:
\[B\left( \frac{\sqrt{3}}{2};\frac{1}{2} \right);\ \ C\left( \frac{\sqrt{3}}{2};\ - \frac{1}{2} \right);\ \ \]
\[\alpha = \frac{\pi}{6};\ \ \beta = \frac{11\pi}{6}.\]
\[B\left( \frac{\sqrt{3}}{2};\frac{1}{2} \right);\ \ C\left( \frac{\sqrt{3}}{2};\ - \frac{1}{2} \right);\ \ \]
\[\alpha = \frac{\pi}{6};\ \ \beta = \frac{11\pi}{6}.\]