TeX Quellcode:

\begin{array}{rcl} \alpha + \beta &=& 120^\circ+\dfrac{ \pi}{6} \cr\cr \alpha + \beta &=& \dfrac{2\pi}{3}+\dfrac{ \pi}{6} \cr\cr \alpha + \beta &=& \dfrac{5 \pi}{6} \cr\cr \alpha + \beta & < & \pi \end{array}