jee-main 2021 Q79

jee-main · India · session4_27aug_shift2 Vectors 3D & Lines MCQ: Relationship Between Two Lines
The angle between the straight lines, whose direction cosines $l , m , n$ are given by the equations $2 l + 2 m - n = 0$ and $m n + n l + \operatorname { lm } = 0$, is: (1) $\frac { \pi } { 3 }$ (2) $\frac { \pi } { 2 }$ (3) $\cos ^ { - 1 } \left( \frac { 8 } { 9 } \right)$ (4) $\pi - \cos ^ { - 1 } \left( \frac { 4 } { 9 } \right)$ 
The angle between the straight lines, whose direction cosines $l , m , n$ are given by the equations $2 l + 2 m - n = 0$ and $m n + n l + \operatorname { lm } = 0$, is:
(1) $\frac { \pi } { 3 }$
(2) $\frac { \pi } { 2 }$
(3) $\cos ^ { - 1 } \left( \frac { 8 } { 9 } \right)$
(4) $\pi - \cos ^ { - 1 } \left( \frac { 4 } { 9 } \right)$
Paper Questions
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