# Help with reciprocal lattices

## Homework Statement

I have to draw a reciprocal lattice of a tetragonal cell with parameters a=3A and c=5A, a body-centred lattice. How do I find a* and c*? I also have to draw an Ewald sphere, and lamda=1.5. However, if I use my solutions (I think they're wrong, see below) I get something that is impossible to draw because the scale is huge.

## Homework Equations

Radius of E sphere= 1/lamda

## The Attempt at a Solution

a*=1/9 and c*= 1/25, the radius= 2/3

haruspex