question_answer

Two lines \[\frac{x-{{x}_{1}}}{{{I}_{i}}}=\frac{y-{{y}_{1}}}{{{m}_{i}}}=\frac{z-{{z}_{1}}}{{{n}_{i}}}(i=1,\,\,2)\] are perpendicular to each other if their direction ratios satisfy

A)  \[{{I}_{i}}={{m}_{i}}={{n}_{i}}\]

B)  \[{{I}_{1}}{{I}_{2}}+{{m}_{1}}{{m}_{2}}+{{n}_{1}}{{n}_{2}}=0\]

C)  \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{{{m}_{1}}}{{{m}_{2}}}=\frac{{{n}_{1}}}{{{n}_{2}}}=0\]

D)  All of these

E)  None of these