Given the plane stress state shown for the material point element, use any calculation method to determine:

a$)$ The maximum and minimum principal stresses.

b$)$ The counter$-$clockwise angle $$ of rotation of the element from the x axis to the x $\text{'}$ axis, where the stresses on the rotated element are ${}_{x^{\text{'}}}=-25\mathrm{.}6$ and ${}_{x^{\text{'}}{y}^{\text{'}}}=10\mathrm{.}2.$

c$)$ Bonus: what is ${}_{y^{\text{'}}}$ in that orientation?