1. The problem statement, all variables and given/known data It is question number 1a here: http://web.utk.edu/~tbarnes/website/cm/cm_hw/hw4/cm_hw4.pdf [Broken] 3. The attempt at a solution I'm not entirely sure how to go about this. I've rearranged this equation to get -3ln(0.33)=Ghkl2<[tex]\delta^2[/tex]> The thing that confuses me is that Ghkl2 is a vector quantity, right? In this case, since we are talking about the (800) plane, would this be just the dot product of G with itself (64)? I'm just not sure how I'm supposed to turn this into a scalar. Any help would be greatly appreciated.