TeX Quellcode:

\begin{array}{rcl}f'_{yx}(x,y) &=& \dfrac{5}{9}\cos(y)e^{\sin(x)+\sin(y)}\cdot\cos(x) \\\\&=& \dfrac{5}{9}\cos(x)\cos(y)e^{\sin(x)+\sin(y)}\end{array}