$\displaystyle - \frac{1}{2}$\displaystyle - \frac{1}{2}

$\displaystyle \frac{1}{2}$\displaystyle \frac{1}{2}

$\displaystyle - \frac{\sqrt{3}}{2 }$\displaystyle - \frac{\sqrt{3}}{2 }

$\displaystyle \frac{\sqrt{3}}{2}$\displaystyle \frac{\sqrt{3}}{2}