Problems $5\mathrm{.}4-7$ through $5\mathrm{.}4-12.$ At a certain point in a member subjected to plane stress, the stresses $\backslash (\backslash$sigma$\_\{$x$\},\backslash$sigma$\_\{$y$\}\backslash ),$ and $\backslash (\backslash$tau$\_\{$x y$\}\backslash )$ have the values shown on Figs. P$5\mathrm{.}4-7$ through P$5\mathrm{.}4-12.($a$)$ Determine the principal stresses and show them on a sketch of a properly oriented stress element, and $($b$)$ determine the shear stress and the normal stress on the planes of maximum shear stress, and show these on a sketch of a properly oriented stress element.