Two vectors $\vec A$ and $\vec B$ have equal magnitudes. The magnitude of $(\vec A + \vec B)$ is $‘n’$ times the magnitude of $(\vec A - \vec B)$. The angle between $ \vec A$ and $\vec B$ is

  • [JEE MAIN 2019]
  • [JEE MAIN 2021]
  • A

    ${\cos ^{ - 1}}\left[ {\frac{{{n^2} - 1}}{{{n^2} + 1}}} \right]$

  • B

    ${\cos ^{ - 1}}\left[ {\frac{{n - 1}}{{n + 1}}} \right]$

  • C

    ${\sin ^{ - 1}}\left[ {\frac{{{n^2} - 1}}{{{n^2} + 1}}} \right]$

  • D

    ${\sin ^{ - 1}}\left[ {\frac{{n - 1}}{{n + 1}}} \right]$

Similar Questions

A particle is situated at the origin of a coordinate system. The following forces begin to act on the particle simultaneously (Assuming particle is initially at rest)

${\vec F_1} = 5\hat i - 5\hat j + 5\hat k$            ${\vec F_2} = 2\hat i + 8\hat j + 6\hat k$

${\vec F_3} =  - 6\hat i + 4\hat j - 7\hat k$         ${\vec F_4} =  - \hat i - 3\hat j - 2\hat k$

Then the particle will move

Let $\overrightarrow C = \overrightarrow A  + \overrightarrow B$

$(A)$ It is possible to have $| \overrightarrow C | < | \overrightarrow A |$ and $ | \overrightarrow C | < | \overrightarrow B|$

$(B)$ $|\overrightarrow C |$  is always greater than $|\overrightarrow A |$

$(C)$ $|\overrightarrow C |$ may be equal to $|\overrightarrow A | + |\overrightarrow B|$

$(D)$ $|\overrightarrow C |$ is never equal to $|\overrightarrow A | + |\overrightarrow B|$

Which of the above is correct

Magnitudes of two vector $\overrightarrow A $ and $\overrightarrow B $ are $4$ units and $3$ units respectively. If these vectors are $(i)$ in same direction $(\theta = 0^o).$ $(ii)$ in opposite direction $(\theta = 180^o)$, then give the magnitude of resultant vector.

$\vec{A}$ is a vector of magnitude $2.7$ units due east. What is the magnitude and direction of vector $4 \vec{A}$ ?

Given below in Column $-I$ are the relations between vectors $\vec a \,$ $\vec b \,$ and $\vec c \,$ and in Column $-II$ are the orientations of $\vec a$, $\vec b$ and $\vec c$ in the $XY-$ plane. Match the relation in Column $-I$ to correct orientations in Column $-II$.

  Column $-I$   Column $-II$
$(a)$ $\vec a \, + \,\,\vec b \, = \,\,\vec c $ $(i)$ Image
$(b)$ $\vec a \, - \,\,\vec c \, = \,\,\vec b$ $(ii)$ Image
$(c)$ $\vec b \, - \,\,\vec a \, = \,\,\vec c $ $(iii)$ Image
$(d)$ $\vec a \, + \,\,\vec b \, + \,\,\vec c =0$ $(iv)$ Image