# Vector problem

1. May 22, 2005

### m00c0w

Hi I was wondering if anyone could help me with this problem:

http://img209.echo.cx/img209/5105/vector5mm.png

In my textbook it says the answer is 1/2(p-q) but I don't understand how that answer is acheived. Any help would be appreciated.

Many thanks.

2. May 22, 2005

### dextercioby

Consider the triangle PMQ.Can u express $\vec{p}$ in terms of $\vec{PM}$ and $\vec{MQ}$...?

And the same for the other triangle...

What relation is there between $\vec{PM}$ and $\vec{MR}$ ?

Daniel.

3. Jun 16, 2005

### m00c0w

In triangle PMQ $\vec{p}$ = $\vec{PM}$ + $\vec{MQ}$.

Also $\vec{PM}$ = $\vec{MR}$ as in they're the same distance. Could anyone explain how I get the answer please? As my test is now tomorrow

4. Jun 16, 2005

### dextercioby

The way i see it

$$\left\{\begin{array}{c}\vec{MQ}+\vec{PM}=\vec{p}\\ \vec{MQ}+\vec{q}=\vec{MR} \end{array} \right$$