The question I'm confused about it below:- A unit cell of copper is cubic FCC. X ray data was measured at Lambda= 1.5406 angstroms. What is the volume? I think to find volume, I need to find lattice constant which is the length of the unit cell. The peaks were given and they are at 43, 50.5, 74, 90 and 95 degrees. These are angles of 2Theta. Do I need to find the crystallographic planes which the angles are reflected from? If so how? I know how to use Bragg's Law and find d spacing. 2dsin(theta)= n(Lambda). Also d= a/SQRT(l^2 + k^2 + h^2) where a is the lattice constant. and l, h and k are Miller indices of the plane.