The direction consines of two lines are related by\[l+m+n=0\]\[a{{l}^{2}}+b{{m}^{2}}+c{{n}^{2}}=0\]. The lines are parallel if

\[{{a}^{-1}}+{{b}^{-1}}+{{c}^{-1}}=0\]

The direction consines of two lines are related by\[l+m+n=0\]\[a{{l}^{

1.	The direction consines of two lines are related by\[l+m+n=0\]\[a{{l}^{2}}+b{{m}^{2}}+c{{n}^{2}}=0\]. The lines are parallel if
A.	\[a+b+c=0\]
B.	\[{{a}^{-1}}+{{b}^{-1}}+{{c}^{-1}}=0\]
C.	\[a=b=c\]
D.	None of these
Answer» C. \[a=b=c\]

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The direction consines of two lines are related by\[l+m+n=0\]\[a{{l}^{2}}+b{{m}^{2}}+c{{n}^{2}}=0\]. The lines are parallel if

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