Answer
(a) greater than
(b) $55^{\circ}$
Work Step by Step
(a) We know that $sin\theta_{r}=\frac{n_{air}}{n_{ice}}sin(\theta_i)$. This equation shows that the angle of refraction decreases as ice melts form water. Thus, the angle of incidence has to be increased in order to keep the same angle of refraction even after the ice is melted.
(b) We know that
$n_{air}sin\theta_i=n_{water}sin(\theta_r)$
We plug in the known values to obtain:
$1\times sin(\theta_i)=1.33\times sin(38^{\circ})$
This simplifies to:
$\theta_i=55^{\circ}$
