For the general $2-$D stress tensor:

$=\left[\begin{array}{cc}{}_{}& {}_{xy}\\ {}_{xy}& {}_{yy}\end{array}\right]$

Prove that the equation for determining the eigenvalues is:

${}^2-2{}_{hyd}+$det$()=0$

Here, ${}_{hyd}$ is the hydrostatic stress tensor as discussed in class, and det$()$ is the determinant of the general stress tensor. $(10$ Points$)$

Hint: treat $$ as any other matrix for which you have to find the eigenvalues, and follow the normal procedure to determine eigenvalues. This will set you on the right path to solve this.