\lim_{ n\to \infty }(1+\frac{1}{n})^{n}=e

(\overrightarrow{OA}×\overrightarrow{OB})·\overrightarrow{OC}=\left| \begin{array}{} a_x & a_y & a_z \ b_x & b_y &b_z \ c_x & c_y & c_z \ \end{array} \right| 

∀\vec{a}∈\mathbb{R}^{3}, ∀\vec{b}∈\mathbb{R}^{3}korral  \; \vec{a}×\vec{b}=-\vec{b}×\vec{a} 