In tungsten, atoms are arranged in all eight corners and has an additional atom in the centre satisfying the body centered cubic lattice condition.

According to Bravis, there are only 14 possible ways of arranging points in space lattice from the 7 crystal systems such that, all the lattice points have exactly the same surrounding.

Radius=1.476 Å or 1.476 × 10^-10 m
Lattice constant for FCC = 4r/√2
Lattice constant = 4.1748 Å.

D = 1.7458 Å = 1.7458 × 10^-10 m
h = 2; k = 2; l = 0
D=a/√(h²+k²+l²)
a = 4.983 Å.

r = 0.123 Å
The lattice constant for BCC = 4r/√3
The lattice constant = 0.2840 Å.