TeX Quellcode:

\begin{array}{rclcl} \cos(\alpha) &=& \dfrac{b}{c} & \vert & \cdot c \cr b &=& c \cdot \cos(\alpha) \cr b &=& 11 \cdot \cos \left( \dfrac{\pi}{8} \right) \cr b & \approx & 10{,}16 \, cm \end{array}