If the radius of the octaheral void is `r` and the radius of the atoms in close-packing is `R`, derive relation between `r` and `R`

Explanation

To derive the relationship between the radius of the octahedral void (r) and the radius of the atoms in close packing (R), we can follow these steps:

### Step 1: Understanding the Geometry
In a close-packed structure, the octahedral void is formed between atoms. We can visualize this by considering a cube where atoms are located at the corners and the center of the cube.

### Step 2: Identifying the Distances
In the cube:
- The distance between two opposite corners of the cube (which is the diagonal) can be represented as \( BC \).
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