A stress tensor at a point $A$ in a continuous medium is given by

$t=([0,b,0],[2,0,c],[a,0,1])$

By determining the constants $a,b,$ and $c$ :

a$.$ Find the principal stresses and their directions.

b$.$ Calculate the maximum shear stress.

$($Note: It is not sufficient to only provide the results. You are expected to show all necessary calculations in detail. Otherwise, no

points will be awarded.$)$