Solution
= Solution
In a <body-centred cubic> lattice, touching atoms lie along a body diagonal. Its length is $\sqrt3a$ and spans four radii, so
$$
\boxed{r=\frac{\sqrt3a}{4}=1.37049\ \text{\AA}=137.05\ \mathrm{pm}}.
$$
= Solution
In a <body-centred cubic> lattice, touching atoms lie along a body diagonal. Its length is $\sqrt3a$ and spans four radii, so
$$
\boxed{r=\frac{\sqrt3a}{4}=1.37049\ \text{\AA}=137.05\ \mathrm{pm}}.
$$