Answer
$\theta=45^{\circ}$
Work Step by Step
We know that;
$dsin(\theta)=m\lambda$
This can be written as:
$sin(\theta)=\frac{m\lambda}{d}$
We plug in the known values to obtain:
$sin(\theta)=\frac{4(589\times 10^{-9})}{3.333\times 10^{-6}}=0.707$
$\theta=45^{\circ}$
