Ответ:
\[B\left( \frac{\sqrt{2}}{2};\frac{\sqrt{2}}{2} \right);\ \ C\left( - \frac{\sqrt{2}}{2};\ - \frac{\sqrt{2}}{2} \right);\ \ \]
\[\alpha = 45{^\circ};\ \ \beta = 225{^\circ}.\]
\[B\left( \frac{\sqrt{2}}{2};\frac{\sqrt{2}}{2} \right);\ \ C\left( - \frac{\sqrt{2}}{2};\ - \frac{\sqrt{2}}{2} \right);\ \ \]
\[\alpha = 45{^\circ};\ \ \beta = 225{^\circ}.\]