Cubic lattices interplanar spacing

The magnitude of the distance between two adjacent and parallel planes of atoms (i.e., the interplanar spacing d, ) is a function of the Miller indices (h, k, and Z) as well as the lattice parameter(s). For example, for crystal structures that have cubic symmetry. 

Periods of lattices a, b, c together with angles a, y, plane indexes (/ , k, 1) and interplanar spacing d are bound by a so-called quadratic form. For the simplest case of a cubic crystal, the quadratic form is presented by the equation... 

---