The position vectors of two adjacent sides $\overrightarrow{O A}$ and $\overrightarrow{O B}$ of a rectangle $O A C B$ are $\vec{a}$ and $\vec{b}$ respectively, where $O$ is the origin. If $16|\vec{a} \times \vec{b}|=3(|\vec{a}|+|\vec{b}|)^2$ and $\theta$ be the acute angle between the diagonals $O C$ and $A B$, then the value of $\tan \left(\frac{\theta}{2}\right)$ is
$\frac{1}{3}$
$\frac{1}{\sqrt{3}}$
$\sqrt{3}$
1
The point of intersection of $\vec{r} \times \vec{a}=\vec{b} \times \vec{a}$ and $\vec{r} \times \vec{b}=\vec{a} \times \vec{b}$, where $\vec{a}=\hat{i}+\hat{j}$ and $\vec{b}=2 \hat{i}-\hat{k}$ is
$3 \hat{i}+2 \hat{j}+\hat{k}$
$\hat{i}-\hat{j}-\hat{k}$
$4 \hat{i}+2 \hat{j}-\hat{k}$
$3 \hat{i}+\hat{j}-\hat{k}$
Let $a_1, a_2, a_3 \ldots$ are in G.P. such that $n>m, a_n>a_m$ and $a_1+a_n=66, a_2 \cdot a_{n-1}=128$. If $\sum_{r=1}^n a_r=126$, then $n$ is
11
8
6
64
The minimum length of intercept on any tangent to the ellipse $\frac{x^2}{4}+\frac{y^2}{9}=1$ cut by the circle $x^2+y^2=25$ is
6
9
11
8
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