P and Q are the midpoints of AB and DC respectively, and $AD\parallel BC$. The position vectors of A, B, C, D are $\vec{

Question

P and Q are the midpoints of AB and DC respectively, and $AD\parallel BC$. The position vectors of A, B, C, D are $\vec{a}, \vec{b}, \vec{c}, \vec{d}$ respectively. The position vector of P is

Accepted Answer

$\frac{\vec{a}+\vec{b}}{2}$

Answer

$\frac{\vec{a}-\vec{b}}{2}$

Answer

$\frac{\vec{a}+\vec{d}}{2}$

Answer

$\frac{\vec{c}+\vec{d}}{2}$

P and Q are the midpoints of AB and DC respectively, and AD∥BCAD\parallel BCAD∥BC. The position vectors of A, B, C, D are a⃗,b⃗,c⃗,d⃗\vec{a}, \vec{b}, \vec{c}, \vec{d}a,b,c respectively. The position vector of P is

P and Q are the midpoints of AB and DC respectively, and $AD\parallel BC$ . The position vectors of A, B, C, D are $\vec{a}, \vec{b}, \vec{c}, \vec{d}$ respectively. The position vector of P is