Figure P$1\mathrm{.}14.$

Figure P$1\mathrm{.}15.$

$1\mathrm{.}15.$ A thin skewed plate is subjected to a uniform distribution of stress along its sides as shown in Fig. P$1\mathrm{.}15.$ Calculate $($a$)$ the stresses ${}_x,{}_y,{}_{xy},$ and $($b$)$ the principal stresses and their orientations.