Координаты точки A (7;2;1) Координаты точки B (5;1; - 2 ) Координаты точки С ( - 3 ; 4;5)...

Решите задачу:

$\overline {a}=\overline {AB}=(-2,-1,-3)\\\\\overline {b}=\overline {BC}=(-8,3,7)\\\\\overline {c}=\overline {AC}=(-10,2,4)\\\\\overline {d}=\overline {BA}=-\overline {a}=(2,1,3)\\\\\overline {p}=\overline {CA}=-\overline {c}=(10,-2,-4)\\\\\overline {k}=3\overline {a}+\overline {b}-\overline {d}=(-16,-1,-5)\\\\\overline {a}\cdot \overline {b}=16-3-21=-8$

$\overline {a}\times \overline {b}= \left|\begin{array}{ccc}i&j&k\\-2&-1&-3\\-8&3&-7\end{array}\right| =\\\\=i\cdot \left|\begin{array}{cc}-1&-3\\3&-7\end{array}\right| -j\cdot \left|\begin{array}{cc}-2&-3\\-8&-7\end{array}\right| +k\cdot \left|\begin{array}{cc}-2&-1\\-8&3\end{array}\right| =\\\\=i(7+9)-j(14-24)+k(-6-8)=16i+10j-14k$