Platinum crystallizes in a face-centered cubic crystal with a unit cell length $\mathrm{\alpha }$. The distance between nearest neighbours is 

We are informed that the FCC lattice is how platinum crystallises. As a result, the radius formula in the FCC lattice is as follows: 

$4r=\sqrt{2a}$

where r = radius and a = edge length

The formula: is used to determine the nearest neighbour atom in the FCC lattice.

$2r=\sqrt{2a}/2$.