Match the following

The postion vectors of vertices of $∆ABC$ are $\overline{a}, \overline{b}, \overline{c}$ and $\overline{a}\cdot \overline{a}=\overline{b}\cdot \overline{b}=\overline{c}\cdot \overline{c}=3, [\overline{a},\overline{b},\overline{c}]=0$ , the postion vector of the orthocentre of $∆ABC$ is

If $\overline{a}, \overline{b}, \overline{c}$ are coplanar vectors and $\overline{a}$ is not parallel to $\overline{b}$ then $\left\{\right(\overline{c}\times \overline{b})\cdot (\overline{a}\times \overline{b}\left)\right\}\overline{a}+\left\{\right(\overline{a}\times \overline{c})\cdot (\overline{a}\times \overline{b}\left)\right\}\overline{b}$ is equal to

Let $\overline{x},\overline{y}\text{ and }\overline{z}$ be unit vectors such that $\overline{x}+\overline{y}+\overline{z}=\overline{a},\overline{x}\cdot \times (\overline{y}+\overline{z})=\overline{b},$ $(\overline{x}\times \overline{y})\times \overline{z}=\overline{c}, \overline{a}\cdot \overline{x}=\frac{3}{2}, \overline{a}\cdot \overline{y}=\frac{7}{4}$ and $\left|\overline{a}\right|=2$ then $\overline{x}=$

Let $\overline{a}, \overline{b} and \overline{c}$ be three non–zero vetors, no two of
which are collinear. If the vector $3\overline{a}+7\overline{b}$ is collinear
with $\overline{c}$ and $3\overline{b}+2\overline{c}$ is collinear with $\overline{a}$, then $21\overline{b}+14\overline{c}=$ 

1/3$(3\overline{a}+4\overline{b}+8\overline{c})$

$-9\overline{a}$

$\left\{\right(\overline{a}\times \overline{b})\cdot (\overline{a}\times \overline{b}\left)\right\}\overline{c}$

$\overline{a}+ \overline{b}+ \overline{c}$