Trong không gian Oxyz cho 2 đường thẳng...

\)">B\in {{d}_{1}}B(1+t;-1-t;2t)C\in {{d}_{2}}C(k;1+2k;k)\overrightarrow{AB}(t;-t-1;2t-1)\overrightarrow{AC}(k-1;2k+1;k-1)A,B,C\overrightarrow{AB}\overrightarrow{AC}\dfrac{t}{k-1}=\dfrac{-t-1}{2k+1}=\dfrac{2t-1}{k-1}\Rightarrow t=1;k=\dfrac{1}{4}\Rightarrow B(2;-2;2);C(\dfrac{1}{4};\dfrac{3}{2};\dfrac{1}{4})\Rightarrow BC=\dfrac{7\sqrt{6}}{4}$