# Vectors help

1. Dec 28, 2008

### tweety1234

1. The problem statement, all variables and given/known data

ST= 2TP. If $$\overrightarrow{TP}=a$$ , $$\overrightarrow{PQ} = b$$ and $$\overrightarrow {QR} = C$$ express in terms of a, b and c

a) $$\overrightarrow{RT}$$

b) $$\overrightarrow{ST}$$

c $$\overrightarrow{SR}$$

http://www.mathhelpforum.com/math-h...h/9244d1230495606-mechanics-help-untitled.jpg

can anyone help me with this question please, I have attached the diagram

thank you!
2. Relevant equations

2. Dec 28, 2008

### rock.freak667

Join R to T and you'll have an enclosed polygon and if all the vector arrows follow the same direction, the resultant is zero.

so TP+ PQ+ QR + RT=0. You can now find RT.

(Triangle law, parallelogram law, polygon law)

3. Dec 28, 2008

### tweety1234

so does RT = a+b+c ?

and how do i find ST and SR?

4. Dec 28, 2008

### tiny-tim

No … TR = a+b+c.

5. Dec 28, 2008

### tweety1234

okay , can you explain that? what does RT equal?

6. Dec 28, 2008

### tiny-tim

ok … TR is the vector from T to R …

you can either go direct,

or you can go any indirect route (that's the way "vector addition" works), provided the arrows follow you all the way.

If you go from R to T, the arrows don't follow you.

If you go from T to R, they do.