Trong không gian Oxyz, cho đường thẳng $d:\left\{ \begin{aligned}...

Đường thẳng d đi qua \)">A\left( 1;2;3 \right)\overrightarrow{a}=\left( 1;1;0 \right).\overrightarrow{a}.\overrightarrow{u}=1.0+1.\left( -7 \right)+0.\left( -1 \right)=-7<0\Rightarrow \left( \overrightarrow{a}.\overrightarrow{u} \right)>90{}^\circ .\overrightarrow{b}=-\dfrac{\overrightarrow{u}}{\left| \overrightarrow{u} \right|}+\dfrac{\overrightarrow{a}}{\left| \overrightarrow{a} \right|}=\dfrac{1}{5\sqrt{2}}\left( 5;12;1 \right)//\left( 5;12;1 \right).\left\{ \begin{aligned}
& x=-4+5t \\
& y=-10+12t \\
& z=2+t \\
\end{aligned} \right..$