# Can anyone tell me formula for lattice $a$, $b$ and $c$ in a hexagonal structure?

Can anyone tell me formula for lattice constants $a$, $b$ and $c$ in a hexagonal structure? $a$ , $b$ and $c$ are units cell of structure. As we see in cubic structure we have a formula to calculate side $a$, $b$ and $c$ method known as braggs law. So what should be the method for calculating it in a hexagonal structure. I want to define the XRD (X-Ray diffraction) structure of my crystal.

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Hello! Please clarify your question . –  ABC Mar 29 '13 at 15:00
more answer needed –  ghanendra Mar 30 '13 at 7:18