\( \def\ds{\displaystyle} \def\R{{\boldsymbol{R}}} \def\m#1{\begin{pmatrix}#1\end{pmatrix}} \def\P{\operatorname{P}} \def\E{\operatorname{E}} \def\Var{\operatorname{Var}} \def\cov{\operatorname{Cov}} \def\Ker{\operatorname{Ker}} \def\Im{\operatorname{Im}} \def\tg{\operatorname{tg}} \def\ctg{\operatorname{ctg}} \def\arctg{\operatorname{arctg}} \def\ge{\geqslant} \def\le{\leqslant} \def\lim{\operatorname*{lim}\limits} \)