TeX Quellcode:
\alpha=\arccos(\frac{\vec r_1 \cdot \vec r_2}{|\vec r_1|\cdot|\vec r_1|})=\arccos(\frac{ x_1\cdot x_2+y_1\cdot y_2+z_1\cdot z_2 }{\sqrt{ x_1^2+y_1^2+z_1^2}\cdot \sqrt{ x_2^2+y_2^2+z_2^2}})