Hey!

Solution is given below :

Since there are four metal atoms in one unit cell, the unit cell is fcc type. For fcc unit cell, radius r=0.3535 a, where a is the edge length of the unit cell. Hence, r=0.3535×361 pm =127.6 pm

Thus, the radius of one atom is 127.6pm.

Hope it helped to clear your delimma

Thank you