$7\mathrm{.}1$ through $7\mathrm{.}4$ For the given state of stress, determine the normal and shearing stresses exerted on the oblique face of the shaded triangular element shown. Use a method of analysis based on the equilibrium of that element, as was done in the derivations of Sec. $7\mathrm{.}1$A$.$

$50\backslash$deg $30$ MPa$40$ MPa