jee-main 2019 Q87

jee-main · India · session2_09apr_shift2 Vectors Introduction & 2D Angle or Cosine Between Vectors
If a unit vector $\vec { a }$ makes angles $\frac { \pi } { 3 }$ with $\hat { i } , \frac { \pi } { 4 }$ with $\hat { j }$ and $\theta \in ( 0 , \pi )$ with $\widehat { k }$, then a value of $\theta$ is:
(1) $\frac { 5 \pi } { 6 }$
(2) $\frac { 5 \pi } { 12 }$
(3) $\frac { \pi } { 4 }$
(4) $\frac { 2 \pi } { 3 }$
If a unit vector $\vec { a }$ makes angles $\frac { \pi } { 3 }$ with $\hat { i } , \frac { \pi } { 4 }$ with $\hat { j }$ and $\theta \in ( 0 , \pi )$ with $\widehat { k }$, then a value of $\theta$ is:\\
(1) $\frac { 5 \pi } { 6 }$\\
(2) $\frac { 5 \pi } { 12 }$\\
(3) $\frac { \pi } { 4 }$\\
(4) $\frac { 2 \pi } { 3 }$