The two-dimensional state of stress, in an infinitesimal element, is given by
$\sigma_{x x}=800 \mathrm{MPa}, \sigma_{x y}=300 \mathrm{MPa}$ and $\sigma_{y y}=0 \mathrm{MPa}$.
Which one of the following options is the maximum shear stress (in $\mathrm{MPa}$) in the element?
- $500$
- $400$
- $800$
- $300$
