# Direction Vector

## Homework Statement

I have two x,y,z coordinates - a & b. I know the distance between the coordinates. I need to get a 3D vector which represent the direction between vector a and vector b.

## Homework Equations

I am unsure as to whether the I should simply substract each respective coordinate value from one to the other i.e. (x1-x2,y1-y2,z1-z2)

## The Attempt at a Solution

I tried to apply the forumula above to a trivial case e.g.

A = (1,1,1); B = (2,2,2); C=(2-1,2-1,2-1,)=(1,1,1)

I am not sure if this is right.

dx
Homework Helper
Gold Member
That's right.

Thanks.

On a side note - how can i calculate the second vector from the first vector and the direction vector? Would l just add the direction vect to the first vector?

dx
Homework Helper
Gold Member
obviously, if d = b - a, then b = a + d!

Thanks again!