$1\mathrm{.}3.$ The stresses at a point with respect to the $xy$ coordinate system are shown in Fig. P$1\mathrm{.}3.$ If

one of the stress components at the same point with respect to the $x^{\text{'}}{y}^{\text{'}}$ coordinate system

is known $($i$.$e$.,{}_{x^{\text{'}}}=18$ksi $),$ determine the other stress components ${}_{y^{\text{'}}}$ and ${}_{x^{\text{'}}{y}^{\text{'}}}$ and the

angle $$ with respect to the $x$ axis.