1. The problem statement, all variables and given/known data An X Ray beam (wavelength 10^10m) is incident upon a sample of a powdered crystalline material. At a distance of 5m from the sample a flat detecting film has been placed. A pattern of 2 circles have been recorded on this film (radius 2cm and 3.5cm). What crystal spacing does this pattern correspond to? 2. Relevant equations I'm not sure but: mλ = 2dsinθ (The reason I am unsure as that is for solid crystals not powder) 3. The attempt at a solution So far I ahve calculated the angles the circles are at to the beam: tan θ = 2/5 so θ = 22 degrees tan θ = 3.5/5 so θ = 35 degrees Next I tried putting them both into the above equation trying to calculate d but that makes little sense to me. Anyone able to help?