Every complex number in the Cartesian form z = x + jy has a polar representationz = r(cos(a) + j sin(a)), where
r = sqrt(x² + y²) and tan(a) = b/a.
In the polar form, finding sqrt is a snap:
sqrt(z) = sqrt(r)(cos(a/2) ± j sin(a/2)).
Also, |1 / z| = 1 / |z|.
Can you take your problem from here?