- A${\tan ^{ - 1}}x$
- ✓$\frac{1}{2}{\tan ^{ - 1}}x$
- C$2{\tan ^{ - 1}}x$
- DNone of these
(Putting $x = \tan \theta )$
$ = {\tan ^{ - 1}}\left[ {\frac{{\sec \theta - 1}}{{\tan \theta }}} \right] = {\tan ^{ - 1}}\left[ {\frac{{1 - \cos \theta }}{{\sin \theta }}} \right]$
$ = {\tan ^{ - 1}}\left[ {\frac{{2\,{{\sin }^2}\frac{\theta }{2}}}{{2\,\sin \frac{\theta }{2}\cos \frac{\theta }{2}}}} \right]$
$ = {\tan ^{ - 1}} (\tan \frac{\theta }{2} )= \frac{\theta }{2} = \frac{1}{2}{\tan ^{ - 1}}x$.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
$\frac{15}{16}$
$\frac{3}{16}$
$-\frac{3}{16}$
$-\frac{16}{3}$
| List $I$ | List $II$ |
| $P.\quad$ Volume of parallelopiped determined by vectors $\vec{a}, \vec{b}$ and $\overrightarrow{ c }$ is $2$ . Then the volume of the parallelepiped determined by vectors $2(\vec{a} \times \vec{b}), 3(\vec{b} \times \vec{c})$ and $(\vec{c} \times \vec{a})$ is | $1.\quad$ $100$ |
| $Q.\quad$ Volume of parallelepiped determined by vectors $\vec{a}, \vec{b}$ and $\vec{c}$ is $5$ . Then the volume of the parallelepiped determined by vectors $3(\overrightarrow{ a }+\overrightarrow{ b }),(\overrightarrow{ b }+\overrightarrow{ c })$ and $2(\overrightarrow{ c }+\overrightarrow{ a })$ is | $2.\quad$ $30$ |
| $R.\quad$ Area of a triangle with adjacent sides determined by vectors $\vec{a}$ and $\vec{b}$ is $20$ . Then the area of the triangle with adjacent sides determined by vectors $(2 \vec{a}+3 \vec{b})$ and $(\vec{a}-\vec{b})$ is | $3.\quad$ $24$ |
| $S.\quad$ Area of a paralelogram with adjacent sides determined by vectors $\vec{a}$ and $\vec{b}$ is $30$ . Then the area of the parallelogram with adjacent sides determined by vectors $(\vec{a}+\vec{b})$ and $\vec{a}$ is | $4.\quad$ $60$ |
Codes: $ \quad P \quad Q \quad R \quad S $

$\vec{a}=3 \hat{i}+\hat{j}-\hat{k},$
$\vec{b}=\hat{i}+b_2 \hat{j}+b_3 \hat{k}, b_2, b_3 \in R ,$
$\vec{c}=c_1 \hat{i}+c_2 \hat{j}+c_3 \hat{k}, c_1, c_2, c_3 \in R$
be three vectors such that $b_2 b_3>0, \vec{a} \cdot \vec{b}=0$ and
$\left(\begin{array}{ccc}0 & -c_3 & c_2 \\ c_3 & 0 & -c_1 \\ -c_2 & c_1 & 0\end{array}\right)\left(\begin{array}{l}1 \\ b_2 \\ b_3\end{array}\right)=\left(\begin{array}{c}3-c_1 \\ 1-c_2 \\ -1-c_3\end{array}\right)$.
Then, which of the following is/are TRUE?
$(A)$ $\overrightarrow{ a } \cdot \overrightarrow{ c }=0$
$(B)$ $\vec{b} \cdot \vec{c}=0$
$(C)$ $|\vec{b}|>\sqrt{10}$
$(D)$ $|\vec{c}| \leq \sqrt{11}$