## anonymous one year ago My question is with respect to PS 1-2b. There appears to some inconsistency between the diagram and the stated solution. It seems that the answer should be the (dir(u)+dir(v))/|dir(u)+dir(v)|, where dir(x) means unit vector in the direction of x.

1. phi

Can you make a screen shot of the question/answer and post it?

2. anonymous

3. phi

It looks like they were sloppy writing up the answer. First, to find the vector that bisects u and v normalize both to the same length (unit length is fine) thus begin with $\hat {u} = \frac{\vec{u}}{|u|}$ and similarly for $$\hat v$$ as noted in the answer, $$\hat u + \hat v$$ bisects the angle between the two vectors. They want the unit length vector. to make this vector unit length , divide by its magnitude, we get $\frac{\hat u + \hat v}{| \hat u + \hat v| }$ this is what I assume you mean by (dir(u)+dir(v))/|dir(u)+dir(v)| notice that the answer starts by stating u and v are unit length and they then give the answer $\frac{u + v}{| u+ v|}$ which is the correct answer (if u and v are unit length) the problem is that u and v in the question are not unit length thus, in the answer, they should have started with $$\hat u$$ and $$\hat v$$ (i.e. u and v normalized to unit length). I would say they were a wee bit sloppy, but their answer is essentially correct. (they should put "hats" over u and v)

4. anonymous

Thanks again phi.