TeX Quellcode:

\begin{array}{rclcl} \left(c\cdot\sin(\alpha)\right)^2+\left(c\cdot\cos(\alpha)\right)^2 &=& c^2 \cr\cr c^2\cdot\sin^2(\alpha)+c^2\cdot\cos^2(\alpha) &=& c^2 \cr\cr c^2\left(\sin^2(\alpha)+\cos^2(\alpha)\right) &=& c^2 &\vert& : c^2 \cr\cr \sin^2(\alpha)+\cos^2(\alpha) &=& 1 \end{array}