Official solution
Let \[\left| z \right| = \left| \omega \right| = r\]
\[\therefore\] \[z = r{e^{i\theta }},\omega = r{e^{i\phi }}\]
where \[\,\,\theta + \phi = \pi .\]
\[\therefore\] \[z = r{e^{i\left( {\pi - \phi } \right)}} = r{e^{i\pi }}.\]
\[{e^{ - i\phi }} = - r{e^{ - i\phi }} = - \overline \omega .\]
[as \[\,\,\,\,\overline \omega = r{e^{ - i\phi }}\] ]