Problem $1$:

$()$ Dr$.$ Mehdi Modares $2024)$ For the state of stress below:

$[]=\left[\begin{array}{ccc}0& & \\ & 0& \\ & & 0\end{array}\right]$MPa

a$)$ Considering $n=\{[1],[2],[2]\},$ obtain the normal and shear stress components on the plane normal to

$\{n\}$ for the state of stress $.$

b$)$ Determine the magnitude of the principal stresses.