Let $\vec{a}, \vec{b}, \vec{c}$ be three vectors such that $|\vec{a}|=\sqrt{31}, 4|\vec{b}|=|\vec{c}|=2$ and $2(\vec{a} \times \vec{b})=3(\vec{c} \times \vec{a})$ If the angle between $\vec{b}$ and $\vec{c}$ is $\frac{2 \pi}{3}$, then $\left(\frac{\vec{a} \times \vec{c}}{\vec{a} \cdot \vec{b}}\right)^2$ is equal to _____
Let $\vec{u}=\hat{i}-\hat{j}-2 \hat{k}, \vec{v}=2 \hat{i}+\hat{j}-\hat{k}, \vec{v} \cdot \vec{w}=2$ and $\vec{v} \times \vec{w}=\vec{u}+\lambda \vec{v}$. Then $\vec{u} \cdot \vec{w}$ is equal to
Let\(\overrightarrow{ a }=2 \hat{i}-7 \hat{j}+5 \hat{k}, \overrightarrow{ b }=\hat{i}+\hat{k} and \overrightarrow{ c }=\hat{i}+2 \hat{j}-3 \hat{k}\) be three given vectors If \(\overrightarrow{ r }\) is a vector such that\( \vec{r} \times \vec{a}=\vec{c} \times \vec{a} \ and \ \vec{r} \cdot \vec{b}=0,\) then \(|\vec{r}|\) is equal to :
The sum of all values of \( \alpha \), for which the points whose position vectors are:
are coplanar, is equal to:
The total number of six digit numbers, formed using the digits 4,5,9 only and divisible by 6 , is __
If ${ }^{2 n+1} P _{n-1}:{ }^{2 n-1} P _n=11: 21$, then $n^2+n+15$ is equal to :
If 2nC3 : nC3 = 10, then \(\frac{n^{2}+3n}{n^{2}-3n+4}\) is equal to