1. C. 1904 I 428
2. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {O = 8\,r^2;d\,O = 16 \cdot r \cdot d\,r;\,m = \frac{{8 \cdot r^3 }}{{3\sqrt 3 }} \cdot s;\,\,d\,m = \frac{{8 \cdot r^2 }}{{\sqrt 3 }} \cdot s \cdot d\,r} \\ {{\rm womit}\,{\rm dann}\,\,d\,O = \frac{{2\sqrt 3 }}{{r \cdot s}} \cdot d\,m = \frac{{3,46}}{{r \cdot s}} \cdot d\,m} \\\end{array} $$\end{document}