1. The problem statement, all variables and given/known data Given this image http://postimg.org/image/m9dyiqwy3/ find the lattice parametre of the reciprocal lattice and the coordinates of the point x. 2. Relevant equations a*=2π(b×c)/(a⋅b×c) b*=2π(c×a)/(b⋅c×a) c*=2π(a×b)/(c⋅a×b) Which are the vectors of the reciprocal lattice a is the lattice parametre 3. The attempt at a solution Since I am studyng a fcc structure, my vectors a,b,c are a=(a/2)(j+k), b=(a/2)(i+k), c=(a/2)(i+j) and the reciprocal's are a*=(-i+ j+ k), b*=(i -j + k), c*=(i+ j -k). This is as far as I can get by myself: My teacher showed that the volume of te reciprocal space is the same as the original, but multiplied by a factor of (4π/a). I know there has to be something which will give me the key to find a*; but I can`t find it myself. Any help is appreciated. Thanks.